Dopaminergic neuron progenitor cell marker 187A5

ABSTRACT

An object of the present invention is to provide a probe, a primer, a primer set and an antibody for use in the detection or selection of a dopaminergic neuron progenitor cell. The present invention provides a probe, a primer and a primer set for use in the detection or selection of a mesencephalon dopaminergic neuron progenitor cell, and preferably a dopaminergic neuron proliferative progenitor cell, which can hybridize with a nucleotide sequence of a 187A5 gene, or a complementary sequence thereto, and an antibody for use in the detection or selection of a mesencephalon dopaminergic neuron progenitor cell, and preferably a dopaminergic neuron progenitor cell, which is capable of binding to a 187A5 protein.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase of PCT/JP2007/058009, filed Apr. 11, 2007, which claims priority to Japanese Patent Application No. 2006-108786, filed Apr. 11, 2006. The contents of all of the aforementioned applications are herein incorporated by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a 187A5 gene, which is a dopaminergic neuron progenitor cell marker. More particularly, the present invention relates to a means for detecting a dopaminergic neuron progenitor cell, a method for detecting the cell, and a kit for detecting the cell.

BACKGROUND ART

The dopamine system is a very important system involved in movement control, hormone secretion control, affectivity control, and so forth, which are important in the mammalian brain. Therefore, abnormalities in dopaminergic neurotransmission cause various disorders of the neural system. For example, the Parkinson's disease is a neurodegenerative disease of the extrapyramidal system which is caused by specific degeneration of dopaminergic neurons in the mesencephalon substantia nigra (HARRISON'S PRINCIPLES OF INTERNAL MEDICINE Vol. 2 23^(rd) ed., Isselbacher et al. edited by McGraw-Hill Inc., NY (1994) pp. 2275-7).

As a method for treating the Parkinson's disease, a method of orally administering L-DOPA (3,4-dihydroxy-phenylalanine) has been mainly adopted for compensating the decrease in the amount of the produced dopamine, but it is known that the duration of the effect is not good.

Accordingly, as a method for compensating the loss of dopaminergic neurons, recently, there has been attempted a therapeutic method of transplanting a mesencephalon ventral region of a 6-9 week aborted fetus containing dopaminergic neuron precursors (U.S. Pat. No. 5,690,927; Spencer et al. (1992) N. Engl. J. Med. 327:1541-8; Freed et al. (1992) N. Engl. J. Med. 327:1549-55; Widner et al. (1992) N. Engl. J. Med. 327:1556-63; Kordower et al. (1995) N. Engl. J. Med. 332:1118-24; Defer et al. (1996) Brain 119:41-50; and Lopez-Lozano et al. (1997) Transp. Proc. 29:977-80). However, at the present time, in addition to cell supply and ethical issues (Rosenstain (1995) Exp. Neurol. 33:106; Turner et al. (1993) Neurosurg. 33:1031-7), various other problems have been indicated, for example, risk of infectious contamination, immunologic transplant rejection (Lopez-Lozano et al. (1997) Transp. Proc. 29:977-80 and Widner and Brudin (1988) Brain Res. Rev. 13:287-324), low survival rate due to the fetus tissue's mainly dependence on lipid metabolism rather than glycolysis (Rosenstein (1995) Exp. Neurol. 33:106), and so forth.

As a method for solving the problem of the ethical issues or supply shortage, for example, a method by using a cortex, a striatum, and mesencephalon cells, derived from a pig, and so forth have been proposed (for example, Japanese Patent Laid-Open Publication No. 10-508487, No. 10-508488, and No. 10-509034). However, in this method, a complex procedure for modifying an antigen on the cell surface (MHC class I antigen) is required to suppress rejection. As a method for solving the transplant rejection, for example, a method involving local immunosuppression by simultaneously transplanting Sertoli cells has been proposed (Japanese Patent Laid-Open Publication No. 11-509170 and No. 11-501818; and Selawly and Cameron (1993) Cell Transplant 2:123-9). It is possible that transplant cells are obtained from a relative whose MHC matches, bone marrow of another person, a bone marrow bank, a cord blood bank, and so forth. However, if patient's own cells can be used, the problems of rejection can be solved without extra procedures and trouble.

Accordingly, it has been expected that, instead of cells derived from an aborted fetus, a differentiation system of dopaminergic neurons in vitro from non-neural cells such as embryo-stem (ES) cell and bone marrow stromal cells are utilized as a transplant material. Actually, it is confirmed that a dopaminergic neuron derived from ES cell is functional for transplantation into lesion striatum of a rat Parkinson's disease model (Kim et al. (2002) Nature 418:50-56). It is thought that in the future, importance of regenerative medicine from ES cells or the patient's own neural stem cells will increase.

On the other hand, in the treatment of damage of neural tissue, restructuring of brain function is required, and for forming appropriate linkage with surrounding cells (network formation), not mature cells but progenitor cells that can differentiate into neurons in vivo are required to be transplanted. However, in the transplantation of neuron progenitor cells, in addition to the above-described problem regarding supply, there is a problem that the progenitor cells can differentiate into a nonuniform cell population. For example, in the treatment of the Parkinson's disease, it is necessary that dopaminergic neurons are selectively transplanted among catecholamine-containing neurons. Before now, as transplant cells for use in the treatment of the Parkinson's disease, there has been proposed a striatum (Lindvall et al. (1989) Arch. Neurol. 46:615-31 and Widner et al. (1992) N. Engl. J. Med. 327:1556-63), an immortalized cell line derived from human embryonic nerve (Japanese Patent Laid-Open Publication No. 8-509215, No. 11-506930, and No. 2002-522070), a post-mitotic human neuron of NT2Z cells (Japanese Patent Laid-Open Publication No. 9-5050554), a neuron primordial cell (Japanese Patent Laid-Open Publication No. 11-509729), a cell transfected with an exogenous gene so as to produce catecholamine such as dopamine, a bone marrow stromal cell (Japanese Patent Laid-Open Publication No. 2002-504503 and No. 2002-513545), an ES cell in which a gene is modified (Kim et al. (2002) Nature 418:50-56), and so forth. However, none of these contain only dopaminergic neurons or cells to differentiate into dopaminergic neurons.

As a method for selectively condensing or isolating dopaminergic neurons from undifferentiated cell population, there has been proposed a method of, introducing a reporter gene expressing a fluorescent protein under control of promoter/enhancer of a gene such as tyrosine hydroxylase (TH) expressed in dopaminergic neurons into each cell of the cell population, isolating the cells emitting fluorescence, and thereby visualizing the alive dopaminergic neurons to condense, segregate or identify (Japanese Patent Laid-Open Publication No. 2002-51775). However, this method requires a complex step of introduction of an exogenous gene, and furthermore, when used in gene treatment, the existence of the reporter gene causes problem of toxicity and immunogenicity.

As described above, now, one of the largest problems in transplantation treatment for the Parkinson's disease is that the either dopaminergic neuron progenitor cells derived from the mesencephalon ventral region of aborted fetus or induced to differentiate are a mixture of various cells. It is desirable that only a desired cell species is isolated and used, considering safety in neural network formation. Furthermore, considering survival or ability for correctly forming a network in a brain in which the cells are transplanted, it can be said that it is desirable from the treatment effect that earlier proliferative progenitor cells are isolated and transplanted.

Before now, as a gene that is expressed in the dopaminergic neuron proliferative progenitor cells, Lrp4 (WO 2004/065599) has been reported. Additionally, some markers of dopaminergic neuron progenitor cells have been reported (WO 2004/038018 and WO 2004/052190).

SUMMARY OF THE INVENTION

In order to isolate a gene selectively expressed in dopaminergic neuron progenitor cells, and preferably dopaminergic neuron proliferative progenitor cells, the present inventors have separated cells positive for an Lrp4 protein, a dopaminergic neuron proliferative progenitor cell marker gene, from the mesencephalon and metencephalon ventral regions of a 13.5-day rat embryo, and have searched a gene specific for the Lrp4-positive cells in the mesencephalon by a subtraction (N-RDA) method. The present inventors have consequently found a gene selectively expressed in dopaminergic neuron proliferative progenitor cells (187A5 gene (hereinafter, occasionally referred to as “187A5”)) (Example 2). The present invention is based on this finding.

An object of the present invention is to provide a means for detecting a dopaminergic neuron progenitor cell (preferably, a dopaminergic neuron proliferative progenitor cell), a method for detecting a dopaminergic neuron progenitor cell (preferably, a dopaminergic neuron proliferative progenitor cell), and a kit for detecting a dopaminergic neuron progenitor cell (preferably, a dopaminergic neuron proliferative progenitor cell).

Further, an object of the present invention is to provide a method for screening for an effective substance for inducing differentiation into a dopaminergic neuron progenitor cell (preferably, a dopaminergic neuron proliferative progenitor cell).

Furthermore, an object of the present invention is to provide a method for producing a dopaminergic neuron progenitor cell (preferably, a dopaminergic neuron proliferative progenitor cell) for use in the treatment of the Parkinson's disease.

The present invention provides a polynucleotide selected from the following (i), (ii), (iii) and (iv) (hereinafter, occasionally referred to as a “187A5 gene”):

(i) a polynucleotide comprising the nucleotide sequence of SEQ ID NO: 1;

(ii) a polynucleotide encoding a protein which consists of an amino acid sequence encoded by a nucleotide sequence of SEQ ID NO: 1 in which one or more nucleotides are inserted, substituted and/or deleted, and/or one or more nucleotides are added to one or both of ends, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; (iii) a polynucleotide which hybridizes under stringent conditions to a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 1, and which encodes a protein functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; and (iv) a polynucleotide which has 70% or more identity with a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 1, and which encodes a protein functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2.

The present invention also provides a protein selected from the following (v), (vi), (vii) and (viii) (hereinafter, occasionally referred to as a “187A5 protein”):

(v) a protein comprising the amino acid sequence of SEQ ID NO: 2;

(vi) a protein which consists of an amino acid sequence of SEQ ID NO: 2 in which one or more amino acids are inserted, substituted and/or deleted, and/or one or more amino acids are added to one or both of ends, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; (vii) a protein which is encoded by a polynucleotide which hybridizes under stringent conditions to a polynucleotide which encodes the amino acid sequence of SEQ ID NO: 2, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; and (viii) a protein which consists of an amino acid sequence having 70% or more identity with the amino acid sequence of SEQ ID NO: 2, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2.

The present invention provides a probe or primer for use in the detection or selection of a dopaminergic neuron progenitor cell (preferably, a dopaminergic neuron proliferative progenitor cell), which can hybridize to a nucleotide sequence of a 187A5 gene, or a complementary sequence thereto (hereinafter, occasionally referred to as a “probe according to the present invention” and a “primer according to the present invention”, respectively).

The present invention provides an antibody for use in the detection or selection of a dopaminergic neuron progenitor cell (preferably, a dopaminergic neuron proliferative progenitor cell), which is capable of binding to a 187A5 protein (hereinafter, occasionally referred to as an “antibody according to the present invention”).

The present invention provides a method for detecting or selecting a dopaminergic neuron progenitor cell (preferably, a dopaminergic neuron proliferative progenitor cell), comprising the step of detecting expression of a 187A5 gene, or a 187A5 protein (hereinafter, occasionally referred to as a “detection method according to the present invention”).

The present invention provides a kit for detecting or selecting a dopaminergic neuron progenitor cell (preferably, a dopaminergic neuron proliferative progenitor cell), comprising at least a probe according to the present invention, a primer according to the present invention, a primer set according to the present invention, or an antibody according to the present invention (hereinafter, occasionally referred to as a “detection kit according to the present invention”).

The present invention provides an agent for detecting or selecting a dopaminergic neuron progenitor cell (preferably, a dopaminergic neuron proliferative progenitor cell), comprising at least a probe according to the present invention, a primer according to the present invention, a primer set according to the present invention, or an antibody according to the present invention (hereinafter, occasionally referred to as an “agent for detection according to the present invention”).

The present invention provides a method for screening for an effective substance for inducing differentiation into a dopaminergic neuron progenitor cell (preferably, a dopaminergic neuron proliferative progenitor cell), comprising the step of detecting expression of a 187A5 gene, or a 187A5 protein.

The present invention provides a method for producing a dopaminergic neuron progenitor cell (preferably, a dopaminergic neuron proliferative progenitor cell) for use in the treatment of the Parkinson's disease.

The probe according to the present invention, the primer according to the present invention, the primer set according to the present invention and the antibody according to the present invention can be used as markers specific for dopaminergic neuron progenitor cells, and preferably dopaminergic neuron proliferative progenitor cells in the mesencephalon. Accordingly, the present invention is extremely useful in a purity test of a transplant material and development of a method for inducing differentiation into a dopaminergic neuron progenitor cell, and preferably a dopaminergic neuron proliferative progenitor cell in vitro, or the like, and largely contributes to the promotion of practical application of regenerative medicine. Moreover, the protein according to the present invention is not merely expressed but has a region expressed in the extracellular space. Accordingly, the extracellular region of the protein according to the present invention can be used as an index for detecting live cells with reliability and for separating and obtaining the cells. Therefore, the present invention is expected to largely contribute to the practical application of regenerative medicine.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an expression period of dopaminergic neuron-related marker genes.

FIG. 2 shows the results of analyzing, by an immunostaining method, protein expressions of Lrp4 and TH in the mesencephalon and metencephalon of a 14.5-day rat embryo.

FIG. 3 shows the results of analyzing, by a RT-PCR method, mRNA expressions of 187A5, Lmx1a and Lrp4 in mesencephalon and metencephalon Lrp4-positive cells.

FIG. 4 shows the results of analyzing, by in situ hybridization, mRNA expressions of 187A5 and Lrp4 in the mesencephalon and metencephalon of a 12.5-day mouse embryo.

FIG. 5 shows the results of analyzing, by a RT-PCR method, mRNA expressions of 187A5, Lmx1a and Lrp4 in dopaminergic neuron proliferative progenitor cells induced to differentiate from ES cells by an SDIA method.

FIG. 6 shows the results of analyzing, by a RT-PCR method, mRNA expressions of 187A5, Lmx1a and Lrp4 in dopaminergic neuron progenitor cells induced to differentiate from ES cells by a 5-stage method.

FIG. 7 shows mouse 187A5 and 187A5-SEAP.

FIG. 8 shows the results of analyzing signal sequence activity of 187A5.

FIG. 9 shows the results of analyzing expression of a 187A5 protein on the cell surface by a biotinylation method of cell surface proteins.

FIG. 10 shows the results of investigating expression of a 187A5 protein on the cell surface by FACS analysis. In the drawing, a boxed area represents 187A5-expressing cells.

FIG. 11 shows the results of analyzing, by an immunostaining method, expression of a 187A5 protein in the mesencephalon and metencephalon ventral regions of an 11.5-day mouse embryo.

FIG. 12 shows the results of investigating, by FACS analysis, expressions of 187A5 and Lrp4 proteins in the mesencephalon and metencephalon ventral regions of a 12.5-day mouse embryo.

FIG. 13 shows the results of investigating, by FACS analysis, expressions of 187A5 and Lrp4 proteins in dopaminergic neuron proliferative progenitor cells induced to differentiate from ES cells by an SDIA method.

FIG. 14 shows the results of separating 187A5/Lrp4-copositive cells induced to differentiate from ES cells by an SDIA method, and culturing.

FIG. 15 schematically shows the structure of a DNA construct that can be used for selecting dopaminergic neuron progenitor cells.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, the present invention will be explained in detail. The following description is an example for explaining the present invention, and the present invention is not limited to the embodiments to be described. All technical terms, scientific terms and terminologies used in the present specification have the same meanings as those that are generally understood by those ordinary skilled in the art in the technical fields to which the present invention belongs, and are used merely for the purpose of explaining a specific embodiment but are not intended to make limitation. The present invention can be carried out in various embodiments as long as not departing from the spirit thereof. All the prior art documents, published publications, patent publications and other patent documents cited in the present specification are incorporated into the present specification as references, and can be used for carrying out the present invention.

[Dopaminergic Neuron Progenitor Cell]

The “dopaminergic neuron progenitor cell”, which is an object to be detected or selected in the present invention, means premature dopaminergic neuron cells.

The “dopaminergic neuron proliferative progenitor cell”, which is also an object to be detected or selected in the present invention, means dopaminergic neuron progenitor cells before arrest of mitotic division.

Dopaminergic neurons differentiate from neuroepithelial cells, through the differentiation stages of proliferative progenitor cells and postmitotic precursor cells, into mature dopaminergic neurons. The dopaminergic neuron progenitor cells are progenitor cells in the dopaminergic neurons. Among them, the dopaminergic neuron proliferative progenitor cell is the earliest progenitor cell in the dopaminergic neurons, and therefore, high survival rate and high ability of network formation in the brain to which the cell is transplanted can be expected. Therefore, the dopaminergic neuron progenitor cell, particularly, the dopaminergic neuron proliferative progenitor cell is useful for the transplantation treatment of diseases caused by decrease in dopamine due to degeneration of the dopaminergic neurons, such as the Parkinson's disease.

The cells selected by using the probe according to the present invention, the primer according to the present invention, the primer set according to the present invention or the antibody according to the present invention as an index are dopaminergic neuron progenitor cells, and therefore, are preferable for the transplantation treatment of neurodegenerative diseases such as the Parkinson's disease in the aspects of safety, survival rate and network formation ability, compared to a conventional mixed cell population or dopaminergic neuron progenitor cells in which an exogenous gene is introduced. Particularly, when the cells detected or selected by using the probe according to the present invention, the primer according to the present invention, the primer set according to the present invention or the antibody according to the present invention are dopaminergic neuron progenitor cells before arrest of mitotic division, namely, dopaminergic neuron progenitor cells in proliferation, the cells have the possibility of differentiating to mature in the most appropriate place in the brain, and also, the dopaminergic neuron progenitor cells have the possibility of proliferating in vivo. Therefore, a longer effect of the treatment can be expected. Therefore, it can be said that the present invention paves the way to the practical application of the effective transplantation treatment of neurodegenerative diseases such as the Parkinson's disease.

[187A5 Gene and Protein]

In the present invention, the “187A5 gene” means those encoding a 187A5 protein and includes not only cDNA but also genomic DNA. It also includes RNA corresponding thereto.

In the present invention, the “187A5 gene”, which is an index for the existence of dopaminergic neuron progenitor cells, has been registered in database as a functionally unknown sequence in mice. However, in humans, rats, bovines, dogs, chimpanzees, and so forth, only predicted sequences of 187A5 genes have been obtained. GenBank Accession Numbers disclosing the respective sequences are as follows.

Human: XM_(—)044062 (SEQ ID NO: 3 (base sequence), SEQ ID NO: 4 (amino acid sequence), hereinafter, representation will be in the same order), AK126715 (SEQ ID NO: 5, SEQ ID NO: 6), HSM803256 (SEQ ID NO: 7, SEQ ID NO: 8), HSM803467 (SEQ ID NO: 9, SEQ ID NO: 10) Mouse: AK028289 (SEQ ID NO: 11, SEQ ID NO: 12), AK157823 (SEQ ID NO: 13 (base sequence)), AK028541 (SEQ ID NO: 14, SEQ ID NO: 15), AK035053 (SEQ ID NO: 16, SEQ ID NO: 17), XM_(—)485684 (SEQ ID NO: 18, SEQ ID NO: 19), AK163356 (SEQ ID NO: 20 (base sequence)) Rat: XM_(—)344107 (SEQ ID NO: 21, SEQ ID NO: 22) Bovine: XM_(—)590147 (SEQ ID NO: 23, SEQ ID NO: 24) Dog: XM_(—)543360 (SEQ ID NO: 25, SEQ ID NO: 26) Chimpanzee: XM_(—)522557 (SEQ ID NO: 27, SEQ ID NO: 28)

In the present invention, a cDNA sequence (SEQ ID NO: 1) of a human 187A5 gene as a gene selectively expressed in dopaminergic neuron progenitor cells (preferably, dopaminergic neuron proliferative progenitor cells) in a mesencephalon site as well as an amino acid sequence (SEQ ID NO: 2) of a human 187A5 protein (polypeptide) as a protein (polypeptide) selectively expressed in dopaminergic neuron progenitor cells (preferably, dopaminergic neuron proliferative progenitor cells) were determined.

Those skilled in the art can specify a nucleotide sequence of a 187A5 gene or an amino acid sequence of a 187A5 protein inherent in various animals based on the nucleotide sequence of the 187A5 gene of SEQ ID NO: 1 and the amino acid sequence of the 187A5 protein of SEQ ID NO: 2. For example, by homology search based on the human or mouse 187A5 gene or 187A5 protein, a 187A5 gene or a 187A5 protein of the animal can be searched and identified. In the homology search, BLAST to be described later or the like can be used. Therefore, in the present invention, the “187A5 gene” and the “187A5 protein” used is meant to include, in addition to a human-derived 187A5 gene or a human-derived 187A5 protein, a 187A5 gene or a 187A5 protein inherent in various animals (preferably, mammals).

The 187A5 gene includes:

a polynucleotide encoding a human 187A5 protein comprising the amino acid sequence of SEQ ID NO: 2, SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8 or SEQ ID NO: 10;

a polynucleotide encoding a mouse 187A5 protein comprising the amino acid sequence of SEQ ID NO: 12, SEQ ID NO: 15, SEQ ID NO: 17 or SEQ ID NO: 19;

a polynucleotide encoding a rat 187A5 protein comprising the amino acid sequence of SEQ ID NO: 22;

a polynucleotide encoding a bovine 187A5 protein comprising the amino acid sequence of SEQ ID NO: 24;

a polynucleotide encoding a dog 187A5 protein comprising the amino acid sequence of SEQ ID NO: 26; and

a polynucleotide encoding a chimpanzee 187A5 protein comprising the amino acid sequence of SEQ ID NO: 28.

Moreover, the 187A5 gene includes:

a polynucleotide comprising the human 187A5 gene nucleotide sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, SEQ ID NO: 7 or SEQ ID NO: 9;

a polynucleotide comprising the mouse 187A5 gene nucleotide sequence of SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18 or SEQ ID NO: 20;

a polynucleotide comprising the rat 187A5 gene nucleotide sequence of SEQ ID NO: 21;

a polynucleotide comprising the bovine 187A5 gene nucleotide sequence of SEQ ID NO: 23; a polynucleotide comprising the dog 187A5 gene nucleotide sequence of SEQ ID NO: 25; and

a polynucleotide comprising the chimpanzee 187A5 gene nucleotide sequence of SEQ ID NO: 27.

The 187A5 gene includes a polynucleotide selected from the following (i′), (ii′), (iii′) and (iv′):

(i′) a polynucleotide comprising the nucleotide sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18, SEQ ID NO: 20, SEQ ID NO: 21, SEQ ID NO: 23, SEQ ID NO: 25 or SEQ ID NO: 27; (ii′) a polynucleotide encoding a protein which consists of an amino acid sequence encoded by a nucleotide sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18, SEQ ID NO: 20, SEQ ID NO: 21, SEQ ID NO: 23, SEQ ID NO: 25 or SEQ ID NO: 27 in which one or more nucleotides are inserted, substituted and/or deleted, and/or one or more nucleotides are added to one or both of ends, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; (iii′) a polynucleotide which hybridizes under stringent conditions to a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18, SEQ ID NO: 20, SEQ ID NO: 21, SEQ ID NO: 23, SEQ ID NO: 25 or SEQ ID NO: 27, and which encodes a protein functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; and (iv′) a polynucleotide which has 70% or more identity with a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18, SEQ ID NO: 20, SEQ ID NO: 21, SEQ ID NO: 23, SEQ ID NO: 25 or SEQ ID NO: 27, and which encodes a protein functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2.

Moreover, the 187A5 gene includes a polynucleotide encoding a protein selected from the following (v′), (vi′), (vii′) and (viii′):

(v′) a protein comprising the amino acid sequence of SEQ ID NO: 2, SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, SEQ ID NO: 22, SEQ ID NO: 24, SEQ ID NO: 26 or SEQ ID NO: 28;

(vi′) a protein which consists of an amino acid sequence of SEQ ID NO: 2, SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, SEQ ID NO: 22, SEQ ID NO: 24, SEQ ID NO: 26 or SEQ ID NO: 28 in which one or more amino acids are inserted, substituted and/or deleted, and/or one or more amino acids are added to one or both of ends, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; (vii′) a protein which is encoded by a polynucleotide which hybridizes under stringent conditions to a polynucleotide which encodes the amino acid sequence of SEQ ID NO: 2, SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, SEQ ID NO: 22, SEQ ID NO: 24, SEQ ID NO: 26 or SEQ ID NO: 28, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; and (viii′) a protein which consists of an amino acid sequence having 70% or more identity with the amino acid sequence of SEQ ID NO: 2, SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, SEQ ID NO: 22, SEQ ID NO: 24, SEQ ID NO: 26 or SEQ ID NO: 28, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2.

According to the present invention, preferably, there is provided a polynucleotide selected from the following (i″), (ii″), (iii″) and (iv″):

(i″) a polynucleotide comprising the nucleotide sequence of SEQ ID NO: 1;

(ii″) a polynucleotide encoding a protein which consists of an amino acid sequence encoded by a nucleotide sequence of SEQ ID NO: 1 in which one or more nucleotides are inserted, substituted and/or deleted, and/or one or more nucleotides are added to one or both of ends, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; (iii″) a polynucleotide which hybridizes under stringent conditions to a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 1, and which encodes a protein functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; and (iv″) a polynucleotide which has 70% or more identity with a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 1, and which encodes a protein functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2.

According to the present invention, preferably, there is also provided a polynucleotide encoding a protein selected from the following (v″), (vi″), (vii″) and (viii″):

(v″) a protein comprising the amino acid sequence of SEQ ID NO: 2;

(vi″) a protein which consists of an amino acid sequence of SEQ ID NO: 2 in which one or more amino acids are inserted, substituted and/or deleted, and/or one or more amino acids are added to one or both of ends, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; (vii″) a protein which is encoded by a polynucleotide which hybridizes under stringent conditions to a polynucleotide which encodes the amino acid sequence of SEQ ID NO: 2, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; and (viii″) a protein which consists of an amino acid sequence having 70% or more identity with the amino acid sequence of SEQ ID NO: 2, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2.

According to the present invention, more preferably, there is provided a human-derived polynucleotide selected from the following (i′″), (ii′″), (iii′″) and (iv′″):

(i′″) a polynucleotide comprising the nucleotide sequence of SEQ ID NO: 1;

(ii′″) a polynucleotide encoding a protein which consists of an amino acid sequence encoded by a nucleotide sequence of SEQ ID NO: 1 in which one or more nucleotides are inserted, substituted and/or deleted, and/or one or more nucleotides are added to one or both of ends, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; (iii′″) a polynucleotide which hybridizes under stringent conditions to a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 1, and which encodes a protein functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; and (iv′″) a polynucleotide which has 95% or more identity with a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 1, and which encodes a protein functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2.

According to the present invention, more preferably, there is also provided a polynucleotide encoding a human-derived protein selected from the following (v′″), (vi′″), (vii′″) and (viii′″):

(v′″) a protein comprising the amino acid sequence of SEQ ID NO: 2;

(vi′″) a protein which consists of an amino acid sequence of SEQ ID NO: 2 in which one or more amino acids are inserted, substituted and/or deleted, and/or one or more amino acids are added to one or both of ends, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; (vii′″) a protein which is encoded by a polynucleotide which hybridizes under stringent conditions to a polynucleotide which encodes the amino acid sequence of SEQ ID NO: 2, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; and (viii′″) a protein which consists of an amino acid sequence having 95% or more identity with the amino acid sequence of SEQ ID NO: 2, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2.

According to the present invention, further preferably, there is provided a human-derived polynucleotide comprising the nucleotide sequence of SEQ ID NO: 1.

According to the present invention, further preferably, there is also provided a polynucleotide encoding a human-derived protein comprising the amino acid sequence of SEQ ID NO: 2.

The 187A5 protein (polypeptide) includes:

a human 187A5 protein comprising the amino acid sequence of SEQ ID NO: 2, SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8 or SEQ ID NO: 10;

a mouse 187A5 protein comprising the amino acid sequence of SEQ ID NO: 12, SEQ ID NO: 15, SEQ ID NO: 17 or SEQ ID NO: 19,

a rat 187A5 protein comprising the amino acid sequence of SEQ ID NO: 22;

a bovine 187A5 protein comprising the amino acid sequence of SEQ ID NO: 24;

a dog 187A5 protein comprising the amino acid sequence of SEQ ID NO: 26; and

a chimpanzee 187A5 protein comprising the amino acid sequence of SEQ ID NO: 28.

Moreover, the 187A5 protein (polypeptide) includes:

a protein which is encoded by a nucleotide sequence comprising the human 187A5 gene nucleotide sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, SEQ ID NO: 7 or SEQ ID NO: 9,

a protein which is encoded by a nucleotide sequence comprising the mouse 187A5 gene nucleotide sequence of SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18 or SEQ ID NO: 20;

a protein which is encoded by a nucleotide sequence comprising the rat 187A5 gene nucleotide sequence of SEQ ID NO: 21;

a protein which is encoded by a nucleotide sequence comprising the bovine 187A5 gene nucleotide sequence of SEQ ID NO: 23;

a protein which is encoded by a nucleotide sequence comprising the dog 187A5 gene nucleotide sequence of SEQ ID NO: 25; and

a protein which is encoded by a nucleotide sequence comprising the chimpanzee 187A5 gene nucleotide sequence of SEQ ID NO: 27.

The 187A5 protein (polypeptide) includes a protein selected from the following (i′), (ii′), (iii′) and (iv′):

(i′) a protein which is encoded by the nucleotide sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18, SEQ ID NO: 20, SEQ ID NO: 21, SEQ ID NO: 23, SEQ ID NO: 25 or SEQ ID NO: 27; (ii′) a protein which consists of an amino acid sequence encoded by a nucleotide sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18, SEQ ID NO: 20, SEQ ID NO: 21, SEQ ID NO: 23, SEQ ID NO: 25 or SEQ ID NO: 27 in which one or more nucleotides are inserted, substituted and/or deleted, and/or one or more nucleotides are added to one or both of ends, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; (iii′) a protein which is encoded by a polynucleotide which hybridizes under stringent conditions to a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18, SEQ ID NO: 20, SEQ ID NO: 21, SEQ ID NO: 23, SEQ ID NO: 25 or SEQ ID NO: 27, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; and (iv′) a protein which is encoded by a polynucleotide which has 70% or more identity with a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, SEQ ID NO: 7, SEQ ID NO: 9, SEQ ID NO: 11, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 16, SEQ ID NO: 18, SEQ ID NO: 20, SEQ ID NO: 21, SEQ ID NO: 23, SEQ ID NO: 25 or SEQ ID NO: 27, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2.

Moreover, the 187A5 protein (polypeptide) includes a protein selected from the following (v′), (vi′), (vii′) and (viii′):

(v′) a protein comprising the amino acid sequence of SEQ ID NO: 2, SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, SEQ ID NO: 22, SEQ ID NO: 24, SEQ ID NO: 26 or SEQ ID NO: 28;

(vi′) a protein which consists of an amino acid sequence of SEQ ID NO: 2, SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, SEQ ID NO: 22, SEQ ID NO: 24, SEQ ID NO: 26 or SEQ ID NO: 28 in which one or more amino acids are inserted, substituted and/or deleted, and/or one or more amino acids are added to one or both of ends, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; (vii′) a protein which is encoded by a polynucleotide which hybridizes under stringent conditions to a polynucleotide which encodes the amino acid sequence of SEQ ID NO: 2, SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, SEQ ID NO: 22, SEQ ID NO: 24, SEQ ID NO: 26 or SEQ ID NO: 28, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; and (viii′) a protein which consists of an amino acid sequence having 70% or more identity with the amino acid sequence of SEQ ID NO: 2, SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 12, SEQ ID NO: 15, SEQ ID NO: 17, SEQ ID NO: 19, SEQ ID NO: 22, SEQ ID NO: 24, SEQ ID NO: 26 or SEQ ID NO: 28, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2.

According to the present invention, preferably, there is provided a protein (polypeptide) selected from the following (i″), (ii″), (iii″) and (iv″):

(i″) a protein which is encoded by the nucleotide sequence of SEQ ID NO: 1;

(ii″) a protein which consists of an amino acid sequence encoded by a nucleotide sequence of SEQ ID NO: 1 in which one or more nucleotides are inserted, substituted and/or deleted, and/or one or more nucleotides are added to one or both of ends, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; (iii″) a protein which is encoded by a polynucleotide which hybridizes under stringent conditions to a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 1, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; and (iv″) a protein which is encoded by a polynucleotide which has 70% or more identity with a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 1, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2.

According to the present invention, preferably, there is also provided a protein (polypeptide) selected from the following (v″), (vi″), (vii″) and (viii″):

(v″) a protein comprising the amino acid sequence of SEQ ID NO: 2;

(vi″) a protein which consists of an amino acid sequence of SEQ ID NO: 2 in which one or more amino acids are inserted, substituted and/or deleted, and/or one or more amino acids are added to one or both of ends, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; (vii″) a protein which is encoded by a polynucleotide which hybridizes under stringent conditions to a polynucleotide which encodes the amino acid sequence of SEQ ID NO: 2, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; and (viii″) a protein which consists of an amino acid sequence having 70% or more identity with the amino acid sequence of SEQ ID NO: 2, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2.

According to the present invention, more preferably, there is provided a human-derived protein (polypeptide) selected from the following (i′″), (ii′″), (iii′″) and (iv′″):

(i′″) a protein which is encoded by the nucleotide sequence of SEQ ID NO: 1;

(ii′″) a protein which consists of an amino acid sequence encoded by a nucleotide sequence of SEQ ID NO: 1 in which one or more nucleotides are inserted, substituted and/or deleted, and/or one or more nucleotides are added to one or both of ends, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; (iii′″) a protein which is encoded by a polynucleotide which hybridizes under stringent conditions to a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 1, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; and (iv′″) a protein which is encoded by a polynucleotide which has 95% or more identity with a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 1, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2.

According to the present invention, more preferably, there is also provided a human-derived protein (polypeptide) selected from the following (v′″), (vi′″), (vii′″) and (viii′″):

(v′″) a protein comprising the amino acid sequence of SEQ ID NO: 2;

(vi′″) a protein which consists of an amino acid sequence of SEQ ID NO: 2 in which one or more amino acids are inserted, substituted and/or deleted, and/or one or more amino acids are added to one or both of ends, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; (vii′″) a protein which is encoded by a polynucleotide which hybridizes under stringent conditions to a polynucleotide which encodes the amino acid sequence of SEQ ID NO: 2, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2; and (viii′″) a protein which consists of an amino acid sequence having 95% or more identity with the amino acid sequence of SEQ ID NO: 2, and which is functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2.

According to the present invention, further preferably, there is provided a human-derived protein encoded by the nucleotide sequence of SEQ ID NO: 1.

According to the present invention, further preferably, there is also provided a human-derived protein comprising the amino acid sequence of SEQ ID NO: 2.

In the present specification, “a polynucleotide in which one or more nucleotides are inserted, substituted and/or deleted, and/or one or more nucleotides are added to one or both of ends” or “an amino acid sequence in which one or more amino acids are inserted, substituted and/or deleted, and/or one or more amino acids are added to one or both of ends” means that the modification is performed by a well-known technical method such as site-directed mutagenesis or by substitution of a plurality of nucleotides or amino acids to an extent of being naturally generated, or the like. In the case of the polynucleotide, the term is meant to include single nucleotide polymorphisms (SNPs). The number of nucleotide or amino acid modifications can be insertion, substitution, deletion, and/or addition to one or both of ends, of, for example, 1 to 30, preferably 1 to 20, more preferably 1 to 10, further preferably one to several (for example, 9 or less), particularly preferably 1 to 4, and most preferably 1 or 2 nucleotides or amino acids.

The modified nucleotide sequence can be preferably a nucleotide sequence of SEQ ID NO: 1 having one or more (for example, one or several, or 1, 2, 3 or 4) mutations without affecting the functions of a protein consisting of the amino acid sequence of SEQ ID NO: 2.

The modified amino acid sequence can be preferably an amino acid sequence of SEQ ID NO: 2 having one or more (for example, one or several, or 1, 2, 3 or 4) conservative substitutions.

The number of insertion, substitution, deletion or addition introduced into the nucleotide sequence in (ii), (ii′), (ii″) or (ii′″) can be preferably one or several (for example, 9 or less), more preferably 1 to 6, particularly preferably 1 to 4, most preferably 1 or 2.

The number of insertion, substitution, deletion or addition introduced into the amino acid sequence in (vi), (vi′), (vi″) or (vi′″) can be preferably one or several (for example, 9 or less), more preferably 1 to 6, particularly preferably 1 to 4, most preferably 1 or 2.

In the present specification, the “conservative substitutions” mean that one or more amino acid residues are substituted with other chemically analogous amino acid residues so as not to substantially change protein functions. For example, the case that a certain hydrophobic residue is substituted with another hydrophobic residue and the case that a certain polar residue is substituted with another polar residue having the same charge can be exemplified. Functionally analogous amino acids which can be substituted in such a manner are known in the technical field, with respect to every amino acid. To give specific examples, non-polar (hydrophobic) amino acids include alanine, valine, isoleucine, leucine, proline, tryptophan, phenylalanine and methionine. Polar (neutral) amino acids include glycine, serine, threonine, tyrosine, glutamine, asparagine and cysteine. Positively charged (basic) amino acids include arginine, histidine and lysine. Negatively charged (acidic) amino acids include aspartic acid and glutamic acid.

The modified nucleotide sequence includes a nucleotide sequence having substitution of guanine to adenine at nucleotide 512 of SEQ ID NO: 1, substitution of guanine to adenine at nucleotide 844 of SEQ ID NO: 1, substitution of guanine to adenine at nucleotide 1360 of SEQ ID NO: 1, substitution of adenine to guanine at nucleotide 2458 of SEQ ID NO: 1 or substitution of adenine to guanine at nucleotide 2991 of SEQ ID NO: 1. The modified nucleotide sequence may have all or some of these substitutions in combination.

The modified amino acid sequence includes an amino acid sequence having substitution of arginine to histidine at amino acid 161 of SEQ ID NO: 2, substitution of valine to isoleucine at amino acid 272 of SEQ ID NO: 2, substitution of valine to isoleucine at amino acid 444 of SEQ ID NO: 2 or substitution of arginine to glycine at amino acid 810 of SEQ ID NO: 2. The modified amino acid sequence may have all or some of these substitutions in combination.

In the present specification, “hybridize under stringent conditions” means hybridization to a target polynucleotide under stringent conditions. Specifically, there can be exemplified a polynucleotide having at least 70% or more, preferably 80% or more, more preferably 85% or more, further preferably 90% or more, further more preferably 95% or more, particularly preferably 98% or more, and most preferably 99% or more identity, with the target nucleotide sequence when calculation is performed using a parameter of default (initial setting) with homology search software such as FASTA, BLAST or Smith-Waterman (Meth. Enzym., 164, 765 (1988)). Moreover, the “stringent conditions” can be performed according to a method of performing reaction in a hybridization buffer that can be generally used by those skilled in the art so that the temperature is 40 to 70° C., and preferably 60 to 65° C., and performing rinsing in a rinse solution whose salt concentration is 15 to 300 mmol/L, and preferably 15 to 60 mmol/L. The temperature and the salt concentration can be appropriately adjusted according to a length of the probe to be used. Furthermore, the condition when the hybridized nucleotide is rinsed can be 0.2 or 2×SSC, 0.1% SDS, and a temperature of 20 to 68° C. As to control of stringent (high stringency) or mild (low stringency) conditions, the difference can be provided by a salt concentration or a temperature in rinsing. When the difference of the hybridization is provided by a salt concentration, a stringent wash buffer (high stringency wash buffer) of 0.2×SSC, 0.1% SDS, or a mild wash buffer (low stringency wash buffer) of 2×SSC, 0.1% SDS can be used. Alternatively, when the difference of the hybridization is provided by a temperature, the temperature is 68° C. in the stringent case, 42° C. in the case of moderate stringency, and room temperature (20 to 25° C.) in the mild case, and every case thereof may be performed under 0.2×SSC, 0.1% SDS.

In general, prehybridization is performed under the same conditions as the hybridization. However, hybridization and preliminary rinsing are not limited to be performed under the same conditions.

The hybridization can be performed according to a known method. Moreover, in the case of using a commercially available library, the hybridization can be performed according to the method described in the appended instruction for use.

In the present specification, the “identity” (occasionally referred to as homology) with respect to amino acid sequences means the degree of identity of the amino acid residues of the respective sequences between the sequences to be compared. In this case, existence of a gap and properties of the amino acids are considered (Wilbur, Natl. Acad. Sci. U.S.A. 80: 726-730 (1983)). For calculation of the homology, commercially available software BLAST (Altschul: J. Mol. Biol. 215: 403-410 (1990)), FASTA (Peasron: Methods in Enzymology 183: 63-69 (1990)), or the like can be used.

The “identity” may be a value calculated by using a homology search program known by those skilled in the art and can be calculated, for example, by using a parameter of default (initial setting) in the homology algorithm BLAST (Basic local alignment search tool) http://www.ncbi.nlm.nih.gov/BLAST/in NCBI (National Center for Biotechnology Information).

The nucleotide sequence having at least 70% or more identity with the nucleotide sequence of SEQ ID NO: 1 can be a nucleotide sequence having preferably 80% or more, more preferably 90% or more, further preferably 90% or more, further more preferably 95% or more, particularly preferably 98% or more, and most preferably 99% or more identity.

The amino acid sequence having at least 70% or more identity with the amino acid sequence of SEQ ID NO: 2 can be an amino acid sequence having preferably 80% or more, more preferably 90% or more, further preferably 90% or more, further more preferably 95% or more, particularly preferably 98% or more, and most preferably 99% or more identity.

In the present invention, if the amino acid sequence of SEQ ID NO: 2 is given, a nucleotide sequence encoding it can be easily determined, and thereby, various nucleotide sequences encoding the amino acid sequence of SEQ ID NO: 2 can be selected. Thus, a polynucleotide encoding a protein consisting of the amino acid sequence of SEQ ID NO: 2 means not only a part or all of a cDNA sequence of SEQ ID NO: 1 but also a cDNA sequence encoding the same amino acids, which has a codon having a degeneracy relationship therewith as a cDNA sequence. Furthermore, the polynucleotide encoding a protein consisting of the amino acid sequence of SEQ ID NO: 2 means even a genomic DNA sequence also containing introns or noncoding regions. In the present invention, it further includes an RNA sequence corresponding thereto.

In the present specification, whether or not to be “functionally equivalent to a protein consisting of the amino acid sequence of SEQ ID NO: 2” can be determined by evaluating a biological phenomenon or functions associated with the expression of the 187A5 gene. For example, it can be determined by evaluating whether or not to be selectively expressed in dopaminergic neuron progenitor cells, and preferably dopaminergic neuron proliferative progenitor cells in the mesencephalon.

The present invention provides a protein comprising a polypeptide consisting of at least 5 amino acid residues (preferably, at least 6 amino acid residues) or all of an amino acid sequence of amino acids 248-397 or 792-877 of SEQ ID NO: 2. This protein corresponds to a high discrimination part in the amino acid sequence of the 187A5 protein, and therefore, can be used as an antigen against an antibody that can discriminate the 187A5 protein with higher accuracy.

The 187A5 protein is a type I single transmembrane protein that is expressed on the cell surface in a direction wherein the N-terminal side thereof can be located in the extracellular space. Thus, by flow cytometry using an antibody capable of binding to the protein, live cells in which the protein is expressed can be separated.

The present invention provides a protein comprising a polypeptide consisting of at least 5 amino acid residues (preferably, at least 6 amino acid residues) or all of an amino acid sequence of amino acids 28 to 927 of SEQ ID NO: 2, amino acids 16 to 1267 of SEQ ID NO: 4, amino acids 1 to 550 of SEQ ID NO: 6, amino acids 1 to 542 of SEQ ID NO: 8, amino acids 1 to 418 of SEQ ID NO: 10, amino acids 76 to 964 of SEQ ID NO: 12, amino acids 40 to 928 of SEQ ID NO: 15, amino acids 1 to 540 of SEQ ID NO: 17, amino acids 40 to 1106 of SEQ ID NO: 19, amino acids 24 to 1524 of SEQ ID NO: 22, amino acids 43 to 1018 of SEQ ID NO: 24, amino acids 43 to 908 of SEQ ID NO: 26 or amino acids 1 to 866 of SEQ ID NO: 28. This protein corresponds to the extracellular region in the amino acid sequence of the 187A5 protein, and therefore, can be used as an antigen for preparing an antibody that can detect live cells as an object to be detected.

The present invention provides use of the protein according to the present invention as an index for detecting or selecting a dopaminergic neuron progenitor cell, and preferably a dopaminergic neuron proliferative progenitor cell.

[Probe, Primer and Primer Set]

The probe or primer according to the present invention for use in the detection or selection of a dopaminergic neuron progenitor cell, and preferably a dopaminergic neuron proliferative progenitor cell can specifically hybridize to a 187A5 gene. According to Example 2, in a 12.5-day mouse embryo which is in the period of generating dopaminergic neurons, mRNA of 187A5 is selectively expressed in the mesencephalon most ventral ventricular zone (ventricular zone; VZ) and the mesencephalon most dorsal roof plate zone in which Lrp4-positive dopaminergic neuron progenitor cells exist, but is not expressed in metencephalon floor plate cells positive for Lrp4. Therefore, it became revealed that mRNA of 187A5 is selectively expressed in dopaminergic neuron proliferative progenitor cells. Accordingly, the expression of the 187A5 gene is useful as an index for dopaminergic neuron progenitor cells. Therefore, the probe, the primer and the primer set according to the present invention can be used as a marker for detecting dopaminergic neuron progenitor cells, and preferably dopaminergic neuron proliferative progenitor cells.

The probe and the primer according to the present invention can be used for detecting expression of a 187A5 gene, and corresponds to a polymer consisting of a plurality of bases or base pairs such as deoxyribonucleic acid (DNA) or ribonucleic acid (RNA). It is known that double-strand cDNA can also be used in tissue in situ hybridization, and such double-strand cDNA is also included in the probe and the primer according to the present invention. As a particularly preferable probe and primer in the detection of RNA in tissue, an RNA probe (riboprobe) can be exemplified.

The probe and the primer according to the present invention include those comprising a nucleotide sequence consisting of at least 10, preferably at least 15 contiguous nucleotides of a nucleotide sequence of a 187A5 gene, or a complementary sequence thereto. Also, the probe and the primer according to the present invention include those comprising a nucleotide sequence consisting of preferably 10 to 50 or 10 to 30, more preferably 15 to 50 or 15 to 30, further preferably 20 to 50 or 20 to 30, further more preferably 25 to 50 or 25 to 30, and most preferably 26 to 39 or 26 to 35 nucleotides.

The probe and the primer according to the present invention can be at least 10 base length, preferably at least 15 base length, more preferably at least 20 base length, and further preferably at least 25 base length. The probe and the primer according to the present invention can also be preferably 10 to 50 base length or 10 to 30 base length, more preferably 15 to 50 base length or 15 to 30 base length, further preferably 20 to 50 base length or 20 to 30 base length, further more preferably 25 to 50 base length or 25 to 30 base length, and most preferably 26 to 39 base length or 26 to 35 base length.

According to preferable embodiments of the probe and the primer according to the present invention, there is provided a polynucleotide for use in the detection or selection of a dopaminergic neuron progenitor cell, and preferably a dopaminergic neuron proliferative progenitor cell in the mesencephalon, comprising a nucleotide sequence consisting of at least 10 (more preferably, at least 15) contiguous nucleotides of a nucleotide sequence of a 187A5 gene, or a complementary sequence thereto and having 15 to 50 base length or 15 to 30 base length, more preferably 25 to 50 base length or 25 to 30 base length, and most preferably 26 to 39 base length or 26 to 35 base length, which can hybridize with a 187A5 gene.

According to preferable embodiments of the probe according to the present invention, there is also provided a polynucleotide that can hybridize to a high discrimination part in the nucleotide sequence of the 187A5 gene. By using such a polynucleotide, it becomes possible to detect the progenitor cells, and preferably the proliferative progenitor cells with higher accuracy. Such a polynucleotide includes a polynucleotide that hybridizes to a nucleotide sequence comprising a part or all of a nucleotide sequence of nucleotides 774 to 1221 or 2403 to 2666 of SEQ ID NO: 1

According to preferable embodiments of the primer according to the present invention, there is also provided those that can amplify a high discrimination part in the nucleotide sequence of the 187A5 gene by a nucleic acid amplification method, and a polynucleotide that can hybridize to the high discrimination part. By using such a polynucleotide, it becomes possible to detect the progenitor cells, and preferably the proliferative progenitor cells with higher accuracy. Such a polynucleotide includes a polynucleotide that can amplify, by a nucleic acid amplification method, a nucleotide sequence comprising a part or all of a nucleotide sequence of nucleotides 774 to 1221 or 2403 to 2666 of SEQ ID NO: 1.

The probe according to the present invention can be used as a probe according to the general methods in known methods for detecting a gene of interest, such as a northern blotting method, a southern blotting method or in situ hybridization method.

The probe according to the present invention can be chemically synthesized based on the nucleotide sequences disclosed in the present specification. The preparation of the probe is well-known and can be performed, for example, according to “Molecular Cloning, A Laboratory Manual 2^(nd) ed.” (Cold Spring Harbor Press (1989)) or “Current Protocols in Molecular Biology” (John Wiley & Sons (1987-1997)).

The primer according to the present invention can also be used as a primer set consisting of two or more primers according to the present invention.

The primer and the primer set according to the present invention can be used as a primer and a primer set according to the general methods in known methods for detecting a gene of interest by using a nucleic acid amplification method such as a PCR method, a RT-PCR method, a real-time PCR method or in situ PCR.

The primer set according to the present invention can be selected so that the nucleotide sequence of the 187A5 gene can be amplified by a nucleic acid amplification method such as a PCR method. The nucleic acid amplification method is well-known, and selection of the primer set in the nucleic acid amplification method is understood by those skilled in the art. For example, in the PCR method, primers can be selected so that one of two primers (primer pair) is paired with the plus strand of the double-strand DNA of the 187A5 gene while the other primer is paired with the minus strand of the double-strand DNA, and with a strand extended by one primer, the other primer can be paired. Moreover, in the LAMP method (WO 00/28082), with respect to the target gene, three regions F3c, F2c and F1c and three regions B1, B2 and B3 are defined from the 3′ end side and from the 5′ end side, respectively, and by using these six regions, four primers can be designed.

The primer according to the present invention can be chemically synthesized based on the nucleotide sequences disclosed in the present specification. The preparation of the primer is well-known and can be performed, for example, according to “Molecular Cloning, A Laboratory Manual 2^(nd) ed.” (Cold Spring Harbor Press (1989)) or “Current Protocols in Molecular Biology” (John Wiley & Sons (1987-1997)).

[Antibody]

The antibody according to the present invention can specifically recognize a 187A5 protein. According to Example 5, it was confirmed that the 187A5 protein exists in dopaminergic neuron progenitor cells. Accordingly, the existence of the 187A5 protein is useful as an index for dopaminergic neuron progenitor cells including dopaminergic neuron proliferative progenitor cells. Therefore, the antibody according to the present invention can be used as a marker for detecting dopaminergic neuron progenitor cells, and preferably dopaminergic neuron progenitor cells.

The 187A5 protein is expressed on the cell surface in a direction wherein the N-terminal side thereof can be located in the extracellular space (Example 4). Therefore, the antibody according to the present invention has the advantage that the dopaminergic neuron progenitor cells can be detected or selected as live cells (Example 6). Moreover, the antibody according to the present invention has the advantage that ES cell-derived cells can also be detected or selected (Example 7).

The 187A5 protein for obtaining the antibody according to the present invention may have antigenicity of 187A5 and includes the above-described protein. Moreover, it includes a protein having an amino acid sequence of the 187A5 protein in which one or more amino acid residues are deleted, inserted, substituted or added. It is known that in such a protein, the same biological activity as the original protein is maintained (Mark et al. (1984) Proc. Natl. Acad. Sci. USA 81: 5662-6; Zoller and Smith (1982) Nucleic Acids Res. 10: 6487-500; Wang et al. (1984) Science 224: 1431-3; and Dalbadie-McFarland et al. (1982) Proc. Natl. Acad. Sci. USA 79: 6409-13). A method by which in a protein, one or more amino acid residues are deleted, inserted, substituted or added in the state of maintaining the antigenicity of the original protein is known. For example, a polynucleotide encoding a mutant protein can be prepared by site-directed mutagenesis and can be appropriately expressed to obtain the protein (Molecular Cloning, A Laboratory Manual 2^(nd) ed., Cold Spring Harbor Press (1989); Current Protocols in Molecular Biology, John Wiley & Sons, (1987-1997), Section 8.1-8.5; Hashimoto-Goto et al. (1995) Gene 152: 271-5; Kinkel (1985) Proc. Natl. Acad. Sci. USA 82: 488-92; Kramer and Fritz (1987) Method. Enzymol 154: 350-67; and Kunkel (1988) Method. Enzymol. 85: 2763-6).

The antibody according to the present invention also includes an antibody specific for a part of a 187A5 protein. Specifically, the 187A5 protein for obtaining the antibody of the present invention includes a polypeptide having the full-length amino acid sequence of the 187A5 protein as well as a polypeptide fragment having a sequence of at least 6 amino acid residues or more (for example, 8, 10, 12 or 15 amino acid residues or more) of the 187A5 protein. The polypeptide fragment of the 187A5 protein in the present specification may be any fragment as long as having the 187A5 protein or antigenicity thereof.

Preferable fragments can include polypeptide fragments such as the amino terminal of the 187A5 protein. The antigenic determinant site of the polypeptide is estimated by a method of analyzing hydrophobicity/hydrophilicity of the amino acid sequence of the protein (Kyte-Doolittle (1982) J. Mol. Biol. 157: 105-22) or a method of analyzing the secondary structure (Chou-Fasman (1978) Ann. Rev. Biochem. 47: 251-76), and furthermore, can be confirmed by a computer program (Anal. Biochem. 151: 540-6 (1985)) or a technique such as a PEPSCAN method (Japanese Patent Laid-Open Publication No. 60-500684) of synthesizing a short peptide and confirming its antigenicity.

The antibody capable of binding to the 187A5 protein includes:

an antibody capable of binding to a protein consisting of the amino acid sequence of SEQ ID NO: 2, SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 8 or SEQ ID NO: 10, or a part thereof;

an antibody capable of binding to a protein consisting of the amino acid sequence of SEQ ID NO: 12, SEQ ID NO: 15, SEQ ID NO: 17 or SEQ ID NO: 19 or, or a part thereof;

an antibody capable of binding to a protein consisting of the amino acid sequence of SEQ ID NO: 22, or a part thereof;

an antibody capable of binding to a protein consisting of the amino acid sequence of SEQ ID NO: 24, or a part thereof;

an antibody capable of binding to a protein consisting of the amino acid sequence of SEQ ID NO: 26, or a part thereof; and

an antibody capable of binding to a protein consisting of the amino acid sequence of SEQ ID NO: 28, or a part thereof.

According to preferable embodiments of the antibody according to the present invention, there is provided an antibody that recognizes a high discrimination polypeptide region in the 187A5 protein. By using such an antibody, it becomes possible to detect the progenitor cells, and preferably the proliferative progenitor cells with higher accuracy. Such an antibody includes an antibody capable of binding to a protein comprising a polypeptide consisting of at least 5 amino acid residues (preferably, at least 6 amino acid residues) or all of an amino acid sequence of amino acids 248 to 397 or 792 to 877 of SEQ ID NO: 2.

According to preferable embodiments of the antibody according to the present invention, there is also provided an antibody that recognizes a polypeptide region expressed in the extracellular space of the 187A5 protein. By using such an antibody, it becomes possible to detect the progenitor cells, and preferably the proliferative progenitor cells as live cells. Such an antibody includes an antibody capable of binding to the polypeptide region expressed in the extracellular space of the 187A5 protein, for example, an antibody capable of binding to a protein comprising a polypeptide consisting of at least 5 amino acid residues (preferably, at least 6 amino acid residues) or all of an amino acid sequence of amino acids 28 to 927 of SEQ ID NO: 2, amino acids 16 to 1267 of SEQ ID NO: 4, amino acids 1 to 550 of SEQ ID NO: 6, amino acids 1 to 542 of SEQ ID NO: 8, amino acids 1 to 418 of SEQ ID NO: 10, amino acids 76 to 964 of SEQ ID NO: 12, amino acids 40 to 928 of SEQ ID NO: 15, amino acids 1 to 540 of SEQ ID NO: 17, amino acids 40 to 1106 of SEQ ID NO: 19, amino acids 24 to 1524 of SEQ ID NO: 22, amino acids 43 to 1018 of SEQ ID NO: 24, amino acids 43 to 908 of SEQ ID NO: 26 or amino acids 1 to 866 of SEQ ID NO: 28.

The antibody according to the present invention can be obtained by using a well-known method for those skilled in the art (for example, “Current Protocols in Molecular Biology” (John Wiley & Sons (1987)) and Antibodies: A Laboratory Manual, Ed. Harlow and David Lane, Cold Spring Harbor Laboratory (1988)).

The antibody according to the present invention includes a polyclonal antibody, a monoclonal antibody, a chimeric antibody, a single-strand antibody (scFv), a humanized antibody, a polyspecific antibody and antibody fragments such as Fab, Fab′, F(ab′)₂, Fc and Fv.

In the case of the polyclonal antibody, the blood of a mammal in which an antigen is sensitized is extracted, and serum can be segregated as polyclonal antibody-containing serum from the blood by a known method.

According to need, fractions containing the polyclonal antibody can also be further isolated from this serum.

In the case of the monoclonal antibody, antibody-producing cells obtained from the spleen or lymph node of the above-described mammal in which an antigen is sensitized are extracted and cell-fused with myeloma cells or the like. The obtained hybridomas (fused cells) are cloned, and antibodies can be collected as the monoclonal antibody from the cultures thereof.

A fragment of the 187A5 protein can be used as the immunizing antigen. Alternatively, those synthesized based on the above-described amino acid sequence can be used. The antigen may be used as a complex with a carrier protein. For preparation of the complex of the antigen and the carrier protein, various condensation agents such as glutaraldehyde, carbodiimide or maleimide-activated ester can be used. The carrier protein may be one generally used such as bovine serum albumin, thyroglobulin or hemocyanin, and a method for coupling at a ratio of 1 to 5 is generally used.

The animal to be immunized includes a mouse, a rat, a hamster, a guinea pig, a rabbit, a cat, a dog, a pig, a goat, a horse and a bovine, and, preferably, includes a mouse, a rat, a rabbit, a guinea pig and a hamster. The injection method includes subcutaneous, muscular or intraperitoneal administration. In the administration, the antigen may be mixed with complete Freund's adjuvant or incomplete Freund's adjuvant. The administration is generally performed once per 2 to 5 weeks.

The antibody-producing cells obtained from the spleen or lymph node of the immunized animal are cell-fused with myeloma cells and isolated as hybridomas. The myeloma cells to be used are derived from a mouse, a rat, a human, or the like, and preferably, derived from the same species as the antibody-producing cells, but cells between different species are occasionally possible.

Operation of the hybridomas (cell fusion) can be performed according to a previously known method, for example, the method disclosed in Nature, 256, 495, 1975. Fusion accelerators include polyethylene glycol and Sendai virus. In general, the cell fusion can be performed by reaction for approximately 1 to 10 minutes so that the ratio between the number of the antibody-producing cells and the number of the myeloma cells is generally approximately 1:1 to 10:1, under a temperature of 20 to 40° C., and preferably 30 to 37° C. by using polyethylene glycol (average molecular weight 1000 to 4000) having a concentration of approximately 20 to 50%.

For screening of the antibody-producing hybridomas, various immunochemical methods can be used, which include an ELISA method by using a microplate coated with the 187A5 protein, an EIA method by using a microplate coated with an anti-immunoglobulin antibody, and an immunoblotting method by using a nitrocellulose transfer membrane after electrophoresing samples containing the 187A5 protein.

From such wells, cloning is further performed, for example, by a limiting dilution method, and thereby, clones can be obtained. Selection and culture of the hybridomas are generally performed in a medium for animal cells (for example, RPMI1640) containing 10 to 20% fetal bovine serum to which HAT (hypoxanthine, aminopterin and thymidine) is added. The clones obtained as described above are transplanted into the peritoneal cavity of an SCID mouse to which pristine is preliminarily administered, and ascitic fluid containing the monoclonal antibody at a high concentration is collected after 10 to 14 days, and can be used as a material for antibody purification. Also, the clones can be cultured, and the cultures thereof can also be used as a material for antibody purification.

For the purification of the monoclonal antibody, a previously known method as an immunoglobulin purification method may be used, and the purification can be easily achieved, for example, by a means such as an ammonium sulfate fraction method, a PEG fraction method, an ethanol fraction method, use of an anion exchanger, or affinity chromatography using the 187A5 protein.

The purification of the polyclonal antibody from the serum can be similarly performed.

[Detection Method]

The expression of the 187A5 gene serves as an index for the existence of dopaminergic neuron progenitor cells, and preferably dopaminergic neuron proliferative progenitor cells, as described above. Therefore, according to the present invention, the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected by detecting expression of a 187A5 gene.

The method for “detecting expression of a 187A5 gene” used herein is not particularly limited as long as being capable of detecting the expression of the 187A5 gene in cell samples to be tested, and can be performed, for example, by the following steps of:

(a) contacting a cell sample to be tested, with the probe, the primer or the primer set according to the present invention; and

(b) detecting the presence or absence of reactivity.

The method for “detecting the presence or absence of reactivity” used herein, for example, includes hybridization methods and nucleic acid amplification methods.

The “cell sample to be tested” used herein may be cell samples that are thought to contain the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells, and, preferably, cells in the mesencephalon ventral region can be used. The cells in the mesencephalon ventral region can be obtained by a known method (Studer, L., et al. Nature Neurosci (1998) 1: 290-295). For example, fetus's (preferably, human aborted fetus's) or patient's own cells of the mesencephalon ventral region can be used as the cell sample to be tested. Moreover, culture cells containing dopaminergic neuron progenitor cells, and preferably dopaminergic neuron proliferative progenitor cells induced to differentiate in vitro can be used. The induction to differentiate into the dopaminergic neuron progenitor cells or the dopaminergic neuron proliferative progenitor cells in vitro can be performed by differentiation treatment by a known method such as an SDIA method (Kawasaki et al. Neuron (2000) 28 (1): 31-40) or a 5-stage method (Lee, S H., et al. Nature Biotech (2000) 18: 675-579) using, as a starting material, cells such as known ES cells (Kawasaki et al. Neuron (2000) 28 (1): 31-40) and Lee, S H., et al. Nature Biotech (2000) 18: 675-579), bone marrow stromal cells, nerve-derived immortalized cell lines (Japanese Patent Laid-Open Publication No. 8-509215, No. 11-506930 and No. 2002-522070) or neuron primordial cells (Japanese Patent Laid-Open Publication No. 11-509729). Preferably, ES cells subjected to the differentiation treatment by the SDIA method can be used as the cell sample to be tested.

The “SDIA method” used herein can be performed by co-culturing ES cells and the stromal cell line PA6 in a serum-free medium (Kawasaki et. al. Neuron. 2000 28 (1): 31-40). Moreover, the “5-stage method” can be performed as follows. ES cells are cultured on a non-adherent culture plate in the presence of serum, and thereby, an embryoid body (EB) is formed. Sequentially, the EB is attached onto an adherent culture plate, and thereby, neuron progenitor cells are selected. Finally, a growth factor such as Shh, FGF2 or FGF8 is added thereto, and thereby, dopaminergic neuron progenitor cells are induced (Lee, S H., et al. Nature Biotech (2000) 18: 675-579).

According to the first embodiment of the detection method according to the present invention, using the probe according to the present invention, the polynucleotide for detection hybridizes to a nucleic acid sample (mRNA or a transcript thereof), and the hybridization complex, namely, the nucleotide double strand, is detected. Thus, the expression of the 187A5 gene can be detected in the cell sample.

For the detailed procedure of the hybridization method, there can be referred to “Molecular Cloning, A Laboratory Manual 2^(nd) ed.” (Cold Spring Harbor Press (1989), particularly, Sections 9.47-9.58), “Current Protocols in Molecular Biology” (John Wiley & Sons (1987-1997), particularly, Sections 6.3-6.4), and “DNA Cloning 1: Core Techniques, A Practical Approach 2^(nd) ed.” (Oxford University (1995), particularly, Section 2.10 for the conditions).

The detection of expression of a 187A5 gene by using the hybridization method can be performed, for example, by the following steps of:

(a-1) contacting a polynucleotide derived from a cell sample to be tested, with the probe according to the present invention; and

(b-1) detecting a hybridization complex.

In step (a-1), mRNA prepared from the cell sample that is thought to contain dopaminergic neuron progenitor cells, and preferably dopaminergic neuron proliferative progenitor cells, or a complementary DNA (cDNA) transcribed from the mRNA can be contacted, as the polynucleotide derived from the cell sample to be tested, with the probe.

In the detection method by using the probe, the probe can be labeled. The label includes a label by using radioactivity (such as ³²P, ¹⁴C and ³⁵S), fluorescence (such as FITC and europium), an enzyme (such as peroxidase or alkaline phosphatase) reaction such as chemical coloring, or the like.

The detection of the hybridization product can be performed by using a well-known method such as northern hybridization, southern hybridization or colony hybridization.

The cells in which the hybridization complex is detected are those expressing a 187A5 gene, and therefore, can be determined as the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells.

According to the second embodiment of the detection method according to the present invention, using the primer or the primer set according to the present invention, a nucleic acid sample (mRNA or a transcript thereof) is amplified by a nucleic acid amplification method, and the amplification product is detected. Thus, the expression of the 187A5 gene can be detected in the cell sample.

The detection of expression of a 187A5 gene by using the nucleic acid amplification method can be performed, for example, by the following steps of:

(a-2) performing a nucleic acid amplification method by using a polynucleotide derived from a cell sample to be tested as a template and the primer or the primer set according to the present invention; and

(b-2) detecting a formed amplification product.

In step (a-2), mRNA prepared from the sample that is thought to contain dopaminergic neuron progenitor cells, and preferably dopaminergic neuron proliferative progenitor cells, or a complementary DNA (cDNA) transcribed from the mRNA can be used as the template.

The detection of the amplification product can be performed by using a nucleic acid amplification method such as a PCR method, a RT-PCR method, a real-time PCR method or a LAMP method.

The cells in which the amplification product is detected are those expressing a 187A5 gene, and therefore, can be determined as the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells.

The 187A5 protein serves as an index for the existence of dopaminergic neuron progenitor cells, and preferably dopaminergic neuron proliferative progenitor cells, as described above. Therefore, according to the present invention, the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected by detecting a 187A5 protein.

The method for “detecting a 187A5 protein” used herein is not particularly limited as long as being capable of detecting the 187A5 protein in cell samples to be tested, and, for example, includes antigen-antibody reaction methods.

According to the third embodiment of the detection method according to the present invention, the antibody according to the present invention and the cell sample are contacted, and the antigen-antibody reaction is detected. Thus, the 187A5 protein can be detected in the cell sample.

The detection of a 187A5 protein by using the antigen-antibody reaction can be performed, for example, by the following steps of:

(c) contacting a protein derived from a cell sample to be tested, with the antibody according to the present invention; and

(d) detecting the presence or absence of reactivity.

The method for “detecting the presence or absence of reactivity” used herein, for example, includes antigen-antibody reaction methods.

The “cell sample to be tested” used herein can be cell samples to be tested that are thought to contain the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells, and are preferably cells in the mesencephalon ventral region or culture cells containing dopaminergic neuron progenitor cells, and preferably dopaminergic neuron proliferative progenitor cells induced to differentiate in vitro. For example, those derived from an embryonic mesencephalon can be used as the cell sample to be tested. The method for obtaining the cell sample to be tested is as described above.

The detection of a 187A5 protein by using the antigen-antibody reaction method can be performed, for example, by the following steps of:

(c-1) contacting a protein derived from a cell sample to be tested, with the antibody according to the present invention; and

(d-1) detecting an antigen-antibody complex.

The method for detecting the antigen-antibody reaction is well-known for those skilled in the art, and, for example, a 187A5 protein can be detected in the cell sample to be tested that is thought to contain dopaminergic neuron progenitor cells, and preferably dopaminergic neuron proliferative progenitor cells, by an immunological method. For the immunological method, a previously known method such as an immunohistologic staining method, an enzyme-linked immunosorbent assay, a western blotting method, an agglutination method, a competition method or a sandwich method, can be applied to the cell sample subjected to appropriate treatment according to need, such as cell separation or extraction operation. The immunohistologic staining method can be performed by, for example, a direct method by using a labeled antibody or an indirect method by using a labeled antibody capable of binding to the antibody. For the labeling agent, a known labeling substance such as a fluorescent substance, a radioactive substance, an enzyme, a metal or a pigment can be used.

The protein derived from a cell sample to be tested is preferably a polypeptide comprising the extracellular region (namely, the N-terminal region).

The cells in which the antigen-antibody complex is detected are those expressing a 187A5 protein, and therefore, can be determined as the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells.

For use in the treatment of the Parkinson's disease, it is desirable that the purity of the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells is high.

The accuracy of the detection or selection of the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be enhanced by performing each of the above-described detection steps not only once but repeatedly.

Therefore, according to the detection method according to the present invention, the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with higher accuracy by performing the above-described step twice or more.

Moreover, the accuracy of the detection or selection of the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be further enhanced by using together other marker genes, preferably a dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene.

Therefore, according to the detection method according to the present invention, the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with higher accuracy by using together a dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene or a protein thereof, a postmitotic dopaminergic neuron precursor cell marker gene or a protein thereof, a dopaminergic neuron progenitor cell marker gene other than the 187A5 gene or a protein thereof, or a mature dopaminergic neuron cell marker gene or a protein thereof, and detecting not only expression of the 187A5 gene, or a protein thereof but also expression of the above-described other marker genes, or the proteins thereof.

Dopaminergic neuron-related marker genes selectively expressed in each of differentiation stages are shown in FIG. 1.

In the detection method characterized in that the expression of the 187A5 gene is detected, the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with high accuracy by using together a dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene or a protein thereof, and detecting not only the 187A5 gene but also expression of the dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene, or the protein thereof.

Specifically, in step (a), the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with high accuracy by using, as the cell sample to be tested, the cells in which the expression of the dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene, or the protein thereof is detected. In this case, the cells in which reactivity is detected (for example, the cells in which the hybridization complex or the amplification product is detected) in step (b) are those which express the 187A5 gene, and which express the dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene or which have the existence of the protein thereof. Thus, the cells can be determined as the detected or selected dopaminergic neuron progenitor cells, and preferably the detected or selected dopaminergic neuron proliferative progenitor cells with high accuracy.

Moreover, the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with high accuracy by performing the method further comprising the step of (e-1) detecting expression of a dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene, or a protein thereof, with respect to the cells in which reactivity is detected (for example, the cells in which the hybridization complex or the amplification product is detected) in step (b). In this case, in step (e-1), the cells in which the expression of the dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene, or the protein thereof is detected are those which express the 187A5 gene, and which express the dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene or which have the existence of the protein thereof. Thus, the cells can be determined as the detected or selected dopaminergic neuron progenitor cells, and preferably the detected or selected dopaminergic neuron proliferative progenitor cells with high accuracy.

In the detection method characterized in that the expression of the 187A5 gene is detected, by using together a postmitotic dopaminergic neuron precursor cell marker gene or a protein thereof, it can be confirmed that the 187A5 gene is expressed but the expression of the postmitotic dopaminergic neuron precursor cell marker gene, or the protein thereof is not detected. Thus, the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with high accuracy.

Specifically, in step (a), the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with high accuracy by using, as the cell sample to be tested, the cells in which the expression of the postmitotic dopaminergic neuron precursor cell marker gene, or the protein thereof is not detected. In this case, the cells in which reactivity is detected (for example, the cells in which the hybridization complex or the amplification product is detected) in step (b) are those which express the 187A5 gene, which do not express the postmitotic dopaminergic neuron precursor cell marker gene, and which do not have the existence of the protein thereof. Thus, the cells can be determined as the detected or selected dopaminergic neuron progenitor cells, and preferably the detected or selected dopaminergic neuron proliferative progenitor cells with high accuracy.

Moreover, the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with high accuracy by performing the method further comprising the step of (e-2) detecting expression of a postmitotic dopaminergic neuron precursor cell marker gene, or a protein thereof, with respect to the cells in which reactivity is detected (for example, the cells in which the hybridization complex or the amplification product is detected) in step (b). In this case, in step (e-2), the cells in which the expression of the postmitotic dopaminergic neuron precursor cell marker gene, or the protein thereof is not detected are those which express the 187A5 gene, which do not express the postmitotic dopaminergic neuron precursor cell marker gene, and which do not have the existence of the protein thereof. Thus, the cells can be determined as the detected or selected dopaminergic neuron progenitor cells, and preferably the detected or selected dopaminergic neuron proliferative progenitor cells with high accuracy.

In the detection method characterized in that the expression of the 187A5 gene is detected, the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with high accuracy by using together a dopaminergic neuron progenitor cell marker gene other than the 187A5 gene or a protein thereof, and detecting not only the 187A5 gene but also expression of the dopaminergic neuron progenitor cell marker gene other than the 187A5 gene, or the protein thereof.

Specifically, in step (a), the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with high accuracy by using, as the cell sample to be tested, the cells in which the expression of the dopaminergic neuron progenitor cell marker gene other than the 187A5 gene, or the protein thereof is detected. In this case, the cells in which reactivity is detected (for example, the cells in which the hybridization complex or the amplification product is detected) in step (b) are those which express the 187A5 gene, and which express the dopaminergic neuron progenitor cell marker gene other than the 187A5 gene or which have the existence of the protein thereof. Thus, the cells can be determined as the detected or selected dopaminergic neuron progenitor cells, and preferably the detected or selected dopaminergic neuron proliferative progenitor cells with high accuracy.

Moreover, the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with high accuracy by performing the method further comprising the step of (e-3) detecting expression of a dopaminergic neuron progenitor cell marker gene other than the 187A5 gene, or a protein thereof, with respect to the cells in which reactivity is detected (for example, the cells in which the hybridization complex or the amplification product is detected) in step (b). In this case, in step (e-3), the cells in which the expression of the dopaminergic neuron progenitor cell marker gene other than the 187A5 gene, or the protein thereof is detected are those which express the 187A5 gene, and which express the dopaminergic neuron progenitor cell marker gene other than the 187A5 gene or which have the existence of the protein thereof. Thus, the cells can be determined as the detected or selected dopaminergic neuron progenitor cells, and preferably the detected or selected dopaminergic neuron proliferative progenitor cells with high accuracy.

In the detection method characterized in that the expression of the 187A5 gene is detected, by using together a mature dopaminergic neuron cell marker gene or a protein thereof, it can be confirmed that the 187A5 gene is expressed but the expression of the mature dopaminergic neuron cell marker gene, or the protein thereof is not detected. Thus, the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with high accuracy.

Specifically, in step (a), the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with high accuracy by using, as the cell sample to be tested, the cells in which the expression of the mature dopaminergic neuron cell marker gene, or the protein thereof is not detected. In this case, the cells in which reactivity is detected (for example, the cells in which the hybridization complex or the amplification product is detected) in step (b) are those which express the 187A5 gene, which do not express the mature dopaminergic neuron cell marker gene, and which do not have the existence of the protein thereof. Thus, the cells can be determined as the detected or selected dopaminergic neuron progenitor cells, and preferably the detected or selected dopaminergic neuron proliferative progenitor cells with high accuracy.

Moreover, the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with high accuracy by performing the method further comprising the step of (e-4) detecting expression of a mature dopaminergic neuron cell marker gene, or a protein thereof, with respect to the cells in which reactivity is detected (for example, the cells in which the hybridization complex or the amplification product is detected) in step (b). In this case, in step (e-4), the cells in which the expression of the mature dopaminergic neuron cell marker gene, or the protein thereof is not detected are those which express the 187A5 gene, which do not express the mature dopaminergic neuron cell marker gene, and which do not have the existence of the protein thereof. Thus, the cells can be determined as the detected or selected dopaminergic neuron progenitor cells, and preferably the detected or selected dopaminergic neuron proliferative progenitor cells with high accuracy.

In the detection method characterized in that the 187A5 protein is detected, the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with high accuracy by using together a dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene or a protein thereof, and detecting not only the 187A5 protein but also expression of the dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene, or the protein thereof.

Specifically, in step (c), the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with high accuracy by using, as the cell sample to be tested, the cells in which the expression of the dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene, or the protein thereof is detected. In this case, the cells in which reactivity is detected (for example, the cells in which the antigen-antibody complex is detected) in step (d) are those which have the existence of the 187A5 protein, and which express the dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene or which have the existence of the protein thereof. Thus, the cells can be determined as the detected or selected dopaminergic neuron progenitor cells, and preferably the detected or selected dopaminergic neuron proliferative progenitor cells with high accuracy.

Moreover, the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with high accuracy by performing the method further comprising the step of (e-1) detecting expression of a dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene, or a protein thereof, with respect to the cells in which reactivity is detected (for example, the cells in which the antigen-antibody complex is detected) in step (d). In this case, in step (e-1), the cells in which the expression of the dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene, or the protein thereof is detected are those which have the existence of the 187A5 protein, and which express the dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene or which have the existence of the protein thereof. Thus, the cells can be determined as the detected or selected dopaminergic neuron progenitor cells, and preferably the detected or selected dopaminergic neuron proliferative progenitor cells with high accuracy.

In the detection method characterized in that the 187A5 protein is detected, by using together a postmitotic dopaminergic neuron precursor cell marker gene or a protein thereof, it can be confirmed that the 187A5 protein is expressed but the expression of the postmitotic dopaminergic neuron precursor cell marker gene, or the protein thereof is not detected. Thus, the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with high accuracy.

Specifically, in step (c), the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with high accuracy by using, as the cell sample to be tested, the cells in which the expression of the postmitotic dopaminergic neuron precursor cell marker gene, or the protein thereof is not detected. In this case, the cells in which reactivity is detected (for example, the cells in which the antigen-antibody complex is detected) in step (d) are those which have the existence of the 187A5 protein, which do not express the postmitotic dopaminergic neuron precursor cell marker gene, and which do not have the existence of the protein thereof. Thus, the cells can be determined as the detected or selected dopaminergic neuron progenitor cells, and preferably the detected or selected dopaminergic neuron proliferative progenitor cells with high accuracy.

Moreover, the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with high accuracy by performing the method further comprising the step of (e-2) detecting expression of a postmitotic dopaminergic neuron precursor cell marker gene, or a protein thereof, with respect to the cells in which reactivity is detected (for example, the cells in which the antigen-antibody complex is detected) in step (d). In this case, in step (e-2), the cells in which the expression of the postmitotic dopaminergic neuron precursor cell marker gene, or the protein thereof is not detected are those which have the existence of the 187A5 protein, which do not express the postmitotic dopaminergic neuron precursor cell marker gene, and which do not have the existence of the protein thereof. Thus, the cells can be determined as the detected or selected dopaminergic neuron progenitor cells, and preferably the detected or selected dopaminergic neuron proliferative progenitor cells with high accuracy.

In the detection method characterized in that the 187A5 protein is detected, the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with high accuracy by using together a dopaminergic neuron progenitor cell marker gene other than the 187A5 gene or a protein thereof, and detecting not only the 187A5 protein but also expression of the dopaminergic neuron progenitor cell marker gene other than the 187A5 gene, or the protein thereof.

Specifically, in step (c), the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with high accuracy by using, as the cell sample to be tested, the cells in which the dopaminergic neuron progenitor cell marker gene other than the 187A5 gene, or the protein thereof is detected. In this case, the cells in which reactivity is detected (for example, the cells in which the antigen-antibody complex is detected) in step (d) are those which have the existence of the 187A5 protein, and which express the dopaminergic neuron progenitor cell marker gene other than the 187A5 gene or which have the existence of the protein thereof. Thus, the cells can be determined as the detected or selected dopaminergic neuron progenitor cells, and preferably the detected or selected dopaminergic neuron proliferative progenitor cells with high accuracy.

Moreover, the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with high accuracy by performing the method further comprising the step of (e-3) detecting expression of a dopaminergic neuron progenitor cell marker gene other than the 187A5 gene, or a protein thereof, with respect to the cells in which reactivity is detected (for example, the cells in which the antigen-antibody complex is detected) in step (d). In this case, in step (e-3), the cells in which the expression of the dopaminergic neuron progenitor cell marker gene other than the 187A5 gene, or the protein thereof is detected are those which have the existence of the 187A5 protein, and which express the dopaminergic neuron progenitor cell marker gene other than the 187A5 gene or which have the existence of the protein thereof. Thus, the cells can be determined as the detected or selected dopaminergic neuron progenitor cells, and preferably the detected or selected dopaminergic neuron proliferative progenitor cells with high accuracy.

In the detection method characterized in that the 187A5 protein is detected, by using together a mature dopaminergic neuron cell marker gene or a protein thereof, it can be confirmed that the 187A5 protein is expressed but the expression of the mature dopaminergic neuron cell marker gene, or the protein thereof is not detected. Thus, the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with high accuracy.

Specifically, in step (c), the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with high accuracy by using, as the cell sample to be tested, the cells in which the expression of the mature dopaminergic neuron cell marker gene, or the protein thereof is not detected. In this case, the cells in which reactivity is detected (for example, the cells in which the antigen-antibody complex is detected) in step (d) are those which have the existence of the 187A5 protein, which do not express the mature dopaminergic neuron cell marker gene, and which do not have the existence of the protein thereof. Thus, the cells can be determined as the detected or selected dopaminergic neuron progenitor cells, and preferably the detected or selected dopaminergic neuron proliferative progenitor cells with high accuracy.

Moreover, the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with high accuracy by performing the method further comprising the step of (e-4) detecting expression of a mature dopaminergic neuron cell marker gene, or a protein thereof, with respect to the cells in which reactivity is detected (for example, the cells in which the antigen-antibody complex is detected) in step (d). In this case, in step (e-4), the cells in which the expression of the mature dopaminergic neuron cell marker gene, or the protein thereof is not detected are those which have the existence of the 187A5 protein, which do not express the mature dopaminergic neuron cell marker gene, and which do not have the existence of the protein thereof. Thus, the cells can be determined as the detected or selected dopaminergic neuron progenitor cells, and preferably the detected or selected dopaminergic neuron proliferative progenitor cells with high accuracy.

“The dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene or the protein thereof” is a “dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene” or a “dopaminergic neuron proliferative progenitor cell marker protein other than the 187A5 protein”.

“The dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene” includes a dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene which is expressed in the mesencephalon most ventral ventricular zone (VZ region), and includes an Lrp4 gene, a Nato3 gene, an Msx1 gene, an Msx2 gene and a Mash1 gene.

The Lrp4 gene is described in WO 2004/065599. The Nato3 gene is described in WO 2007/021003. The Msx1 gene and the Msx2 gene are described in WO 2007/021004. The Mash1 gene is described in Kele J, Simplicio N, Ferri A L, Mira H, Guillemot F, Arenas E, Ang S L. Neurogenin 2 is required for the development of ventral mesencephalon dopaminergic neurons. Development. 2006 February; 133 (3): 495-505.

The detection of the dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene is not particularly limited as long as using a method by which expression of the known gene can be detected, and, for example, includes the hybridization method and the nucleic acid amplification method, as described above.

“The dopaminergic neuron proliferative progenitor cell marker protein other than the 187A5 protein” includes a dopaminergic neuron proliferative progenitor cell marker protein other than the 187A5 protein which is expressed in the mesencephalon most ventral ventricular zone (VZ region), and, preferably, includes a protein detected only in dopaminergic neuron proliferative progenitor cells.

Such a protein includes proteins of an Lrp4 gene, a Nato3 gene, an Msx1 gene, an Msx2 gene and a Mash1 gene.

The detection of the dopaminergic neuron proliferative progenitor cell marker protein other than the 187A5 protein is not particularly limited as long as using a method by which expression of the known protein can be detected, and, for example, includes the antigen-antibody reaction method, as described above.

“The postmitotic dopaminergic neuron precursor cell marker gene or the protein thereof” includes a gene expressed in the mesencephalon most ventral mantle layer (ML region) or a protein thereof, and includes a Nurr1 gene, an En1 gene, an En2 gene, a Ptx3 gene and a TH gene. Moreover, the marker gene includes a gene expressed in the mesencephalon most ventral ventricular zone (VZ region) or a protein thereof, and includes a 65B13 gene.

The Nurr1 gene is described in Science. 1997 11; 276 (5310): 248-50. The En1 gene is described in J. Neurosci. 2001 21 (9): 3126-34. The En2 gene is described in J. Neurosci. 2001 21 (9): 3126-34. The Ptx3 gene is described in Proc. Natl. Acad. Sci. 1997 94: 13305-10. The TH gene is described in Science. 1997 11; 276 (5310): 248-50. The 65B13 gene is described in WO 2004/038018.

The detection of the postmitotic dopaminergic neuron precursor cell marker gene or the protein thereof is not particularly limited as long as using a method by which expression of the known gene or the protein thereof can be detected, and, for example, includes the hybridization method, the nucleic acid amplification method and the antigen-antibody reaction method, as described above.

“The dopaminergic neuron progenitor cell marker gene other than the 187A5 gene or the protein thereof” is a “dopaminergic neuron progenitor cell marker gene other than the 187A5 gene” or a “dopaminergic neuron progenitor cell marker protein other than the 187A5 protein”.

“The dopaminergic neuron progenitor cell marker gene other than the 187A5 gene” includes a dopaminergic neuron progenitor cell marker gene other than the 187A5 gene which is expressed in the mesencephalon most ventral region, and includes an Lmx1a gene.

The Lmx1a gene is described in WO 2005/052190.

The detection of the dopaminergic neuron progenitor cell marker gene other than the 187A5 gene is not particularly limited as using a method by which expression of the known gene can be detected, and, for example, includes the hybridization method and the nucleic acid amplification method, as described above.

“The dopaminergic neuron progenitor cell marker protein other than the 187A5 protein” includes a dopaminergic neuron progenitor cell marker protein other than the 187A5 protein which is expressed in the mesencephalon most ventral region. Such a protein includes a protein of an Lmx1a gene.

The detection of the dopaminergic neuron progenitor cell marker protein other than the 187A5 protein is not particularly limited as long as using a method by which expression of the known protein can be detected, and, for example, includes the antigen-antibody reaction method, as described above.

“The mature dopaminergic neuron cell marker gene” includes a DAT gene.

The DAT gene is described in Development 2003 131: 1145-55.

The detection of the mature dopaminergic neuron cell marker gene or the protein thereof is not particularly limited as long as using a method by which expression of the known gene or the protein thereof can be detected, and, for example, includes the hybridization method, the nucleic acid amplification method and the antigen-antibody reaction method, as described above.

Moreover, the accuracy of the detection or selection of the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be further enhanced by using together a vector comprising a gene construct in which a promoter of the 187A5 gene is operably linked to a marker gene.

Therefore, according to the detection method according to the present invention, the dopaminergic neuron progenitor cells, and preferably the dopaminergic neuron proliferative progenitor cells can be detected or selected with higher accuracy by using together a gene construct in which a promoter of the 187A5 gene is operably linked to a marker gene, and detecting not only expression of the 187A5 gene, or the protein thereof but also expression of the marker gene.

The detection of the dopaminergic neuron progenitor cells by using the vector comprising a gene construct in which a promoter of the 187A5 gene is operably linked to a marker gene can be performed, for example, according to Japanese Patent Laid-Open Publication No. 2002-51775.

A marker gene that can be detected under the control of a promoter/enhancer of the 187A5 gene expressed in dopaminergic neuron progenitor cells is introduced into each cell in a cell population, and the expression of the marker gene is detected. Thus, the dopaminergic neuron progenitor cells can be detected.

Specifically, the dopaminergic neuron progenitor cells can be detected or selected by performing the steps of transforming the cell sample to be tested, with a vector comprising a gene construct in which a promoter of the gene according to the present invention is operably linked to a marker gene, and detecting expression of the marker gene in the cell sample to be tested. In this case, in the step, the cells in which the expression of the marker gene is detected can be determined as the detected or selected dopaminergic neuron progenitor cells, and preferably the detected or selected dopaminergic neuron proliferative progenitor cell with high accuracy.

The nucleotide sequence of the “promoter of the gene according to the present invention” used herein includes a nucleotide sequence of a promoter region obtained by expression region analysis of the 187A5 gene to be described later, and also includes a modified sequence thereof having approximately equivalent promoter activity.

The “marker gene” used herein may be a marker gene that can be detected under the control of a promoter/enhancer of the 187A5 gene, and includes GFP.

The “gene construct” used herein may have a structure in which the 187A5 gene is linked upstream or downstream of the marker gene under the control of an expression control sequence (including a promoter, an enhancer, or the like) of the 187A5 gene. In addition, a gene encoding the maker can be knocked in to the 187A5 gene locus. As preferable embodiments of the gene construct, constructs having structures schematically described in 2 to 4 in FIG. 15 can be exemplified.

[Detection Kit]

The present invention provides a detection kit for performing the detection method according to the present invention.

The first embodiment of the detection kit according to the present invention includes a detection kit for performing the first embodiment of the detection method according to the present invention, and specifically, includes a kit for detecting expression of a 187A5 gene, comprising at least the probe according to the present invention. This probe may be labeled. The detection kit detects the expression of the 187A5 gene by a hybrid formation method. Therefore, the detection kit of the first embodiment can optionally further include various reagents for performing the hybrid formation method, for example, a substrate compound for use in the detection of a label, a hybridization buffer, instructions, equipment, and/or so forth.

Moreover, a detection kit for performing the detection with high accuracy includes the kit further comprising a probe, a primer, a primer set or an antibody which can detect expression of a dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene, or a protein thereof, expression of a postmitotic dopaminergic neuron precursor cell marker gene, or a protein thereof, expression of a dopaminergic neuron progenitor cell marker gene other than the 187A5 gene, or a protein thereof, or expression of a mature dopaminergic neuron cell marker gene, or a protein thereof. The probe, the primer, the primer set or the antibody may be labeled. By any of the hybrid formation method, the nucleic acid amplification method and the antigen-antibody reaction method, the detection kit further detects the expression of the dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene, or the protein thereof, the expression of the postmitotic dopaminergic neuron precursor cell marker gene, or the protein thereof, the expression of the dopaminergic neuron progenitor cell marker gene other than the 187A5 gene, or the protein thereof, or the expression of the mature dopaminergic neuron cell marker gene, or the protein thereof.

The second embodiment of the detection kit according to the present invention includes a detection kit for performing the second embodiment of the detection method according to the present invention, and specifically, includes a kit for detecting expression of a 187A5 gene, comprising at least the primer according to the present invention or the primer set according to the present invention. The detection kit detects the expression of the 187A5 gene by the nucleic acid amplification method. Therefore, the detection kit of the second embodiment can optionally further include various reagents for performing the nucleic acid amplification method, for example, a buffer, an internal standard indicating that the amplification reaction can normally progress, instructions, equipment, and/or so forth.

Moreover, a detection kit for performing the detection with high accuracy includes the kit further comprising a probe, a primer, a primer set or an antibody which can detect expression of a dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene, or a protein thereof, expression of a postmitotic dopaminergic neuron precursor cell marker gene, or a protein thereof, expression of a dopaminergic neuron progenitor cell marker gene other than the 187A5 gene, or a protein thereof, or expression of a mature dopaminergic neuron cell marker gene, or a protein thereof. The probe, the primer, the primer set or the antibody may be labeled. By any of the hybrid formation method, the nucleic acid amplification method and the antigen-antibody reaction method, the detection kit further detects the expression of the dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene, or the protein thereof, the expression of the postmitotic dopaminergic neuron precursor cell marker gene, or the protein thereof, the expression of the dopaminergic neuron progenitor cell marker gene other than the 187A5 gene, or the protein thereof, or the expression of the mature dopaminergic neuron cell marker gene, or the protein thereof.

The third embodiment of the detection kit according to the present invention includes a detection kit for performing the third embodiment of the detection method according to the present invention, and specifically, includes a kit for detecting a 187A5 protein, comprising at least the antibody according to the present invention. This antibody may be labeled. The detection kit detects the expression of the 187A5 protein by detecting the antigen-antibody reaction. Therefore, the detection kit of the third embodiment can optionally further include various reagents for performing the antigen-antibody reaction, for example, a secondary antibody for use in an ELISA method or the like, a coloring reagent, a buffer, instructions, equipment, and/or so forth.

Moreover, a detection kit for performing the detection with high accuracy includes the kit further comprising a probe, a primer, a primer set or an antibody which can detect expression of a dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene, or a protein thereof, expression of a postmitotic dopaminergic neuron precursor cell marker gene, or a protein thereof, expression of a dopaminergic neuron progenitor cell marker gene other than the 187A5 gene, or a protein thereof, or expression of a mature dopaminergic neuron cell marker gene, or a protein thereof. The probe, the primer, the primer set or the antibody may be labeled. By any of the hybrid formation method, the nucleic acid amplification method and the antigen-antibody reaction method, the detection kit further detects the expression of the dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene, or the protein thereof, the expression of the postmitotic dopaminergic neuron precursor cell marker gene, or the protein thereof, the expression of the dopaminergic neuron progenitor cell marker gene other than the 187A5 gene, or the protein thereof, or the expression of the mature dopaminergic neuron cell marker gene, or the protein thereof.

Furthermore, a detection kit for performing the detection with high accuracy includes the detection kits of the first to third embodiment according to the present invention, further comprising a vector comprising a gene construct in which a promoter of the 187A5 gene is operably linked to a marker gene.

[Agent for Detection]

The present invention provides an agent for detection for performing the detection method according to the present invention.

The first embodiment of the agent for detection according to the present invention includes an agent for detection for performing the first embodiment of the detection method according to the present invention, and specifically, includes an agent for detecting expression of a 187A5 gene, comprising at least the probe according to the present invention. This probe may be labeled. The agent for detection detects the expression of the 187A5 gene by a hybrid formation method. Therefore, the agent for detection of the first embodiment can optionally further includes various reagents for performing the hybrid formation method, for example, a substrate compound for use in the detection of a label, a hybridization buffer, instructions, equipment, and/or so forth.

Moreover, an agent for detection for performing the detection with high accuracy includes the agent for detection further comprising a probe, a primer, a primer set or an antibody which can detect expression of a dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene, or a protein thereof, expression of a postmitotic dopaminergic neuron precursor cell marker gene, or a protein thereof, expression of a dopaminergic neuron progenitor cell marker gene other than the 187A5 gene, or a protein thereof, or expression of a mature dopaminergic neuron cell marker gene, or a protein thereof. The probe, the primer, the primer set or the antibody may be labeled. By any of the hybrid formation method, the nucleic acid amplification method and the antigen-antibody reaction method, the agent for detection further detects the expression of the dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene, or the protein thereof, the expression of the postmitotic dopaminergic neuron precursor cell marker gene, or the protein thereof, the expression of the dopaminergic neuron progenitor cell marker gene other than the 187A5 gene, or the protein thereof, or the expression of the mature dopaminergic neuron cell marker gene, or the protein thereof.

The second embodiment of the agent for detection according to the present invention includes an agent for detection for performing the second embodiment of the detection method according to the present invention, and specifically, includes an agent for detecting expression of a 187A5 gene, comprising at least the primer according to the present invention or the primer set according to the present invention. The agent for detection detects the expression of the 187A5 gene by the nucleic acid amplification method. Therefore, the agent for detection of the second embodiment can optionally further include various reagents for performing the nucleic acid amplification method, for example, a buffer, an internal standard indicating that the amplification reaction can normally progress, instructions, equipment, and/or so forth

Moreover, an agent for detection for performing the detection with high accuracy includes the agent for detection further comprising a probe, a primer, a primer set or an antibody which can detect expression of a dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene, or a protein thereof, expression of a postmitotic dopaminergic neuron precursor cell marker gene, or a protein thereof, expression of a dopaminergic neuron progenitor cell marker gene other than the 187A5 gene, or a protein thereof, or expression of a mature dopaminergic neuron cell marker gene, or a protein thereof. The probe, the primer, the primer set or the antibody may be labeled. By any of the hybrid formation method, the nucleic acid amplification method and the antigen-antibody reaction method, the agent for detection further detects the expression of the dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene, or the protein thereof, the expression of the postmitotic dopaminergic neuron precursor cell marker gene, or the protein thereof, the expression of the dopaminergic neuron progenitor cell marker gene other than the 187A5 gene, or the protein thereof, or the expression of the mature dopaminergic neuron cell marker gene, or the protein thereof.

The third embodiment of the agent for detection according to the present invention includes an agent for detection for performing the third embodiment of the detection method according to the present invention, and specifically, includes a agent for detecting a 187A5 protein, comprising at least the antibody according to the present invention. This antibody may be labeled. The agent for detection detects the expression of the 187A5 protein by detecting the antigen-antibody reaction. Therefore, the agent for detection of the third embodiment can optionally further include various reagents for performing the antigen-antibody reaction, for example, a secondary antibody for use in an ELISA method or the like, a coloring reagent, a buffer, instructions, equipment, and/or so forth.

Moreover, an agent for detection for performing the detection with high accuracy includes the agent for detection further comprising a probe, a primer, a primer set or an antibody which can detect expression of a dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene, or a protein thereof, expression of a postmitotic dopaminergic neuron precursor cell marker gene, or a protein thereof, expression of a dopaminergic neuron progenitor cell marker gene other than the 187A5 gene, or a protein thereof, or expression of a mature dopaminergic neuron cell marker gene, or a protein thereof. The probe, the primer, the primer set or the antibody may be labeled. By any of the hybrid formation method, the nucleic acid amplification method and the antigen-antibody reaction method, the agent for detection further detects the expression of the dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene, or the protein thereof, the expression of the postmitotic dopaminergic neuron precursor cell marker gene, or the protein thereof, the expression of the dopaminergic neuron progenitor cell marker gene other than the 187A5 gene, or the protein thereof, or the expression of the mature dopaminergic neuron cell marker gene, or the protein thereof.

Furthermore, an agent for detection for performing the detection with high accuracy includes the agents for detection of the first to third embodiment according to the present invention, further comprising a vector comprising a gene construct in which a promoter of the 187A5 gene is operably linked to a marker gene.

[Screening Method]

The detection method according to the present invention can be applied to screening for an effective substance for inducing differentiation into a dopaminergic neuron progenitor cell. Specifically, whether or not the addition of a candidate substance has induced the differentiation into a dopaminergic neuron progenitor cell, and preferably a dopaminergic neuron proliferative progenitor cell is determined by using expression of a 187A5 gene, or a protein thereof as an index, and thereby, the effective substance for inducing differentiation into a dopaminergic neuron progenitor cell can be screened for.

Therefore, the present invention provides a method for screening for an effective substance for inducing differentiation into a dopaminergic neuron progenitor cell, comprising the following steps of:

(i) contacting a cell that can differentiate into a dopaminergic neuron progenitor cell, with a substance to be tested; and

(ii) detecting expression of a 187A5 gene, or a protein thereof in the cell that has been contacted with the substance to be tested.

The cell that can differentiate into a dopaminergic neuron progenitor cell in step (i) is preferably a cell that can differentiate into a dopaminergic neuron proliferative progenitor cell, and can be preferably collected from an embryonic mesencephalon or from culture cells containing neuron progenitor cells induced to differentiate from ES cells.

“Contacting with a substance to be tested” in step (i) can be performed, for example, by adding the substance to be tested to culture cells containing the cell that can differentiate into a dopaminergic neuron progenitor cell, and preferably a dopaminergic neuron proliferative progenitor cell.

The “substance to be tested” includes a synthesized low-molecular compound, a protein, a synthesized peptide, a purified or partially purified polypeptide, an antibody, a bacterium-releasing material (including bacterial metabolites) and a nucleic acid (such as antisense, ribozyme and RNAi), and is preferably a compound or a salt thereof, or a solvate thereof (for example, a hydrate), but is not limited thereto. The “substance to be tested” may be a novel substance or a known substance.

In step (ii), according to the detection method according to the present invention, the expression of the 187A5 gene, or the protein thereof can be detected.

Specifically, steps (a-1) and (b-1) are performed for the detection by using the hybridization method. Steps (a-2) and (b-2) are performed for the detection by using the nucleic acid amplification method. Steps (c-1) and (d-1) are performed for the detection by using the antigen-antibody reaction method. Thus, the expression of the 187A5 gene, or the protein thereof can be detected.

In step (ii), when the expression of the 187A5 gene, or the protein thereof is detected in the cell sample to be tested by contacting the substance to be tested, the substance can be determined as the effective substance for inducing differentiation into a dopaminergic neuron progenitor cell, and preferably a dopaminergic neuron proliferative progenitor cell.

The substance specified by the screening method according to the present invention can be used as the effective substance for inducing differentiation into a dopaminergic neuron progenitor cell, and preferably a dopaminergic neuron proliferative progenitor cell.

The present invention provides the method for screening for an effective substance for inducing differentiation into a dopaminergic neuron progenitor cell, further comprising the following step of:

(iii-1) detecting expression of a dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene, or a protein thereof in the cell that has been contacted with the substance to be tested.

When the expression of the 187A5 gene, or the protein thereof is detected in step (ii), and the expression of the dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene, or the protein thereof is detected in step (iii-1), the substance can be determined as the effective substance for inducing differentiation into a dopaminergic neuron progenitor cell, and preferably a dopaminergic neuron proliferative progenitor cell, with high accuracy.

Step (iii-1) may be performed after step (i) and may be performed before or after step (ii).

The present invention provides the method for screening for an effective substance for inducing differentiation into a dopaminergic neuron progenitor cell, further comprising the following step of:

(iii-2) detecting expression of a postmitotic dopaminergic neuron precursor cell marker gene, or a protein thereof in the cell that has been contacted with the substance to be tested.

When the expression of the 187A5 gene, or the protein thereof is detected in step (ii), but the postmitotic dopaminergic neuron precursor cell marker gene or the protein thereof is not detected in step (iii-2), the substance can be determined as the effective substance for inducing differentiation into a dopaminergic neuron progenitor cell, and preferably a dopaminergic neuron proliferative progenitor cell, with high accuracy.

Step (iii-2) may be performed after step (i) and may be performed before or after step (ii).

“The dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene or the protein thereof” is a “dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene” or a “dopaminergic neuron proliferative progenitor cell marker protein other than the 187A5 protein”.

“The dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene” includes a dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene which is expressed in the mesencephalon most ventral ventricular zone (VZ region), and includes an Lrp4 gene, a Nato3 gene, an Msx1 gene, an Msx2 gene and a Mash1 gene.

The detection of the dopaminergic neuron proliferative progenitor cell marker gene other than the 187A5 gene is not particularly limited as long as using a method by which the expression of the known gene can be detected, and, for example, includes the hybridization method and the nucleic acid amplification method.

“The dopaminergic neuron proliferative progenitor cell marker protein other than the 187A5 protein” includes a dopaminergic neuron proliferative progenitor cell marker protein other than the 187A5 protein which is expressed in the mesencephalon most ventral ventricular zone (VZ region), and, preferably, includes a protein detected only in dopaminergic neuron proliferative progenitor cells.

Such a protein includes proteins of an Lrp4 gene, a Nato3 gene, an Msx1 gene, an Msx2 gene and a Mash1 gene.

The detection of the dopaminergic neuron proliferative progenitor cell marker protein other than the 187A5 protein is not particularly limited as long as using a method by which the expression of the known protein can be detected, and, for example, includes the antigen-antibody reaction method.

“The postmitotic dopaminergic neuron precursor cell marker gene or the protein thereof” includes a gene expressed in the mesencephalon most ventral mantle layer (ML region) or a protein thereof, and includes a Nurr1 gene, an En1 gene, an En2 gene, a Ptx3 gene and a TH gene. Moreover, the marker gene or the protein thereof includes a gene expressed in the mesencephalon most ventral ventricular zone (VZ region) or a protein thereof, and includes a 65B13 gene.

The detection of the postmitotic dopaminergic neuron precursor cell marker gene or the protein thereof is not particularly limited as long as using a method by which the expression of the known gene or the protein thereof can be detected, and, for example, includes the hybridization method, the nucleic acid amplification method and the antigen-antibody reaction method.

The present invention provides the method for screening for an effective substance for inducing differentiation into a dopaminergic neuron progenitor cell, further comprising the following step of:

(iii-3) transforming the cell that has been contacted with the substance to be tested, with a vector comprising a gene construct in which a promoter of the 187A5 gene is operably linked to a marker gene, and detecting expression of the marker gene in the cell.

When the expression of the 187A5 gene, or the protein thereof is detected in step (ii), and the expression of the marker gene is detected in step (iii-3), the substance can be determined as the effective substance for inducing differentiation into a dopaminergic neuron progenitor cell, and preferably a dopaminergic neuron proliferative progenitor cell, with high accuracy.

Step (iii-3) may be performed after step (i) and may be performed before or after step (ii). Furthermore, step (iii-3) may be performed after step (iii-1) or (iii-2).

[Production Method]

The detection method according to the present invention can detect or select dopaminergic neuron progenitor cells. The dopaminergic neuron progenitor cells can be used in the treatment of the Parkinson's disease. Therefore, the dopaminergic neuron progenitor cells for use in the treatment of the Parkinson's disease can be produced from dopaminergic neuron progenitor cells detected or selected by using expression of a 187A5 gene, or a protein as an index.

The dopaminergic neuron progenitor cells used herein are preferably dopaminergic neuron proliferative progenitor cells.

The present invention provides a method for producing a dopaminergic neuron progenitor cell, comprising the following steps of:

(i) obtaining cells that can contain a dopaminergic neuron progenitor cell;

(ii) detecting or selecting the dopaminergic neuron progenitor cell by using the detection method according to the present invention; and

(iii) culturing the cell obtained in step (ii).

The present invention provides a therapeutic agent for the Parkinson's disease, comprising dopaminergic neuron progenitor cells, and preferably dopaminergic neuron proliferative progenitor cells detected or selected by the detection method according to the present invention.

The present invention provides use of dopaminergic neuron progenitor cells, and preferably dopaminergic neuron proliferative progenitor cells detected or selected by the detection method according to the present invention, for the production of a drug for use in the treatment of the Parkinson's disease.

The present invention provides a method for treating the Parkinson's disease, comprising transplanting dopaminergic neuron progenitor cells, and preferably dopaminergic neuron proliferative progenitor cells detected or selected by the detection method according to the present invention, into the brain of a mammal including a human.

In the present specification, the “detection” also includes “discrimination”. Moreover, the “detection” includes not only the case that cells as an object are discriminated as being cells of a particular kind but also the case that cells as an object are discriminated as not being cells of a particular kind.

EXAMPLES Example 1 Isolation and Sequence Analysis of Dopaminergic Neuron Progenitor Cell-Selective Gene

An Lrp4 gene has been identified as a cell surface marker for separating dopaminergic neuron proliferative progenitor cells (WO 2004/065599). By using an anti-Lrp4 antibody, it becomes possible to separate dopaminergic neuron proliferative progenitor cells derived from ES cells. Thus, hereinafter, the isolation and sequence analysis of a gene selective for dopaminergic neuron proliferative progenitor cells will be described.

(1) Isolation of Lrp4-Positive Cell

First, the mesencephalon and metencephalon ventral regions of a 13.5-day rat embryo were dispersed by using the accumax (MS Techno Systems), and then, without being subjected to fixation and permeabilization treatments, the cells were stained for 30 minutes at 4° C. by using an anti-Lrp4 monoclonal antibody (obtained from hybridomas (Deposition No. FERM BP-10315 and No. FERM BP-10316), diluted to 1/10, 1% fetal bovine serum (JRH), 5% fetal rat serum (JRH), 1 mM EDTA (Invitrogen)/PBS (Sigma)). Then, by using an FACS buffer (PBS+1% fetal bovine serum (JRH)+1 mM EDTA), rinsing was performed for 3 minutes at 4° C. three times, and the cells were stained for 20 minutes at 4° C. by using a PE-labeled anti-hamster IgG antibody (Becton Dickinson, 8 μg/ml, 1% fetal bovine serum, 5% fetal rat serum, 1 mM EDTA/PBS). Then, rinsing was performed in the same manner. After the staining, Lrp4-positive cells were separated by a cell sorter (FACS vantage SE, Becton Dickinson) (FIG. 2). The total RNA was prepared from the cells immediately after the separation by using the RNeasy mini kit (Qiagen), and double-strand cDNA was synthesized by using the cDNA synthesis kit (TAKARA). Next, the synthesized cDNA was digested with the restriction enzyme RsaI (TAKARA), and then, ad2 was added thereto. The cDNA was amplified by PCR using ad2S as a primer.

The amplification was carried out under the conditions that incubation was performed for 5 minutes at 72° C., then, reactions for 30 seconds at 94° C., for 30 seconds at 65° C. and for 2 minutes at 72° C. were performed at 20 cycles, and finally, incubation was performed for 2 minutes at 72° C.

(SEQ ID NO: 29) ad2S: CAGCTCCACAACCTACATCATTCCGT (SEQ ID NO: 30) ad2A: ACGGAATGATGT

PCR was performed by using a reaction solution with the following composition.

10xExTaq 5 μl 2.5 mM dNTP 4 μl ExTaq 0.25 μl   100 μM primer 0.5 μl   cDNA 2 μl Distilled water 38.25 μl   

Next, by using the cDNAs corresponding to the amplified cDNA of 4 ng, 0.4 ng and 0.04 ng as templates, PCR was performed in the following reaction system.

10xExTaq 1 μl 2.5 mM dNTP 0.8 μl ExTaq 0.05 μl 100 μM primer 0.1 μl for each cDNA 1 μl Distilled water 6.95 μl

After Incubation for 2 minutes at 94° C., the amplification reactions were performed for 30 seconds at 94° C., for 30 seconds at 65° C. and for 2 minutes at 72° C., and finally, incubation was performed for 2 minutes at 72° C. The amplifications of PCR were performed at 26 cycles.

The following primers were used in the PCR.

(SEQ ID NO: 31) Lrp4: TAGTCTACCACTGCTCGACTGTAACG (SEQ ID NO: 32) CAGAGTGAACCCAGTGGACATATCTG (SEQ ID NO: 33) Lmx1a: TGGTTCAGGTGTGGTTCCAGAACCAG (SEQ ID NO: 34) GAGTTGTAGACGCTCTGTTCAATGGC

As a result, the Lrp4 gene is expressed at the approximately equal level in any of the mesencephalon and metencephalon Lrp4-positive cells. However, it was confirmed that an Lmx1a gene (WO 2005/052190), which is a marker gene of dopaminergic neurons and dopaminergic neuron progenitor cells, is strongly expressed only in the mesencephalon Lrp4-positive cells (FIG. 3). Therefore, it is thought that the mesencephalon Lrp4-positive cells contain the dopaminergic neuron proliferative progenitor cells, but the metencephalon Lrp4-positive cells do not contain the dopaminergic neuron proliferative progenitor cells.

Thus, next, by using this sample, a gene specific for the Lrp4-positive cells in the mesencephalon was searched by a subtraction (N-RDA) method (described in WO 2004/065599). As a result, one (187A5) of the isolated cDNA fragments was a fragment encoding a functionally unknown gene. Next, expression of this gene was confirmed by the above-described RT-PCR method using the following primers.

(SEQ ID NO: 35) 187A5: ACCAGGAAGGACAATGCCATTCGTCC (SEQ ID NO: 36) CCTTCTTCACCTTGGCTCTTAGGATG

As a result, it was confirmed that the 187A5 gene is specifically expressed in the Lrp4-positive cells in the mesencephalon in the same manner as the Lmx1a gene (FIG. 3).

(2) Sequence Analysis

As a result of database search, rat and mouse cDNA sequences that are thought to be the full length of this gene were obtained (for example, Sequence Number: Mouse 187A5 AK028289, Mouse 187A5 AK157823 (frame shift), Mouse 187A5 AK028541, Mouse 187A5 XM_(—)485684 (alternative), Mouse 187A5 AK163356 (frame shift), Rat 187A5 XM_(—)344107 (predicted)). A partial sequence (SEQ ID NO: 1) that is thought to be a human homologous gene was also obtained, but the full length could not be obtained. Thus, homology search was performed with respect to the human genomic sequence, and a human cDNA sequence was predicted. However, for the neighborhood of the 5′ end, a region having high homology could not be found. Therefore, sequence determination was performed by using a 5′ RACE method.

From 1 μg of human embryonic brain mRNA (Clontech), cDNA was amplified by using the 5′ RACE core kit (TAKARA), and self-ligation was performed. By using the following primers, the cDNA 5′ end was amplified. The obtained fragments were cloned into pCRII (Invitrogen), and sequence determination was performed.

(SEQ ID NO: 37) RT Reaction: CATCCCAGTCTC (SEQ ID NO: 38) Primary PCR: TGGAGAAGGTTGTGCCTCTGGACTTG (SEQ ID NO: 39) CTGGTTGGCTTCCTTGAGGAAGAAGG (SEQ ID NO: 40) Secondary PCR: TCCTGCGGGACAAAGTCTACCTGAGC (SEQ ID NO: 41) CTGAGGATGTGGTAGCTCACAGGTAG

The PCR reaction was performed with the following composition.

10xExTaq 5 μl 2.5 mM dNTP 4 μl ExTaq 0.25 μl 100 μM primer 0.5 μl for each Template 1 μl DMSO 1.5 μl Distilled water 37.25 μl

After incubation for 2 minutes at 94° C., the amplification reactions were performed for 30 seconds at 94° C., for 30 seconds at 65° C. and for 2 minutes at 72° C., and finally, incubation was performed for 2 minutes at 72° C. The amplifications of PCR were performed at 35 cycles for primary PCR, and secondary PCR was performed by using the primary PCR products diluted 10-fold as templates and performing amplifications at 20 cycles.

Next, in order to confirm that the predicted sequence is correct, each of three divided regions thereof was amplified by RT-PCR. The PCR products were cloned into pCRII (Invitrogen), and sequence determination was performed.

From 0.5 μg of human embryonic brain mRNA (Clontech), cDNA was amplified by using the RNA PCR kit (TAKARA). By using the cDNA as a template, PCR was performed.

The neighborhood of the 5′ end was amplified by using the following primers.

(SEQ ID NO: 42) Human 187A5 F4: GAGGTCGACGCCACCATGCGCTCCGAGGGTGCGG CCCCC (SEQ ID NO: 43) Human 187a5 R1: GGGTCCATAGCTGGCATTGAGCACTG

The PCR reaction was performed with the following composition.

10xLATaq 5 μl MgCl₂ 5 μl 2.5 mM dNTP 8 μl LATaq 0.5 μl 100 μM primer 0.5 μl for each cDNA 1 μl DMSO 1.5 μl Distilled water 28 μl

After incubation for 2 minutes at 94° C., the amplification reactions for 30 seconds at 94° C., for 30 seconds at 65° C. and for 3.5 minutes at 72° C. were performed at 35 cycles, and finally, incubation was performed for 2 minutes at 72° C.

The remaining regions were amplified by using the following primers F12 and R5 as well as F13 and R4 in combination.

(SEQ ID NO: 44) Human 187A5 F12: CTACCTGTGAGCTACCACATCCTCAG (SEQ ID NO: 45) Human 187A5 R5: TTCTCTGCCAGGATGGAGTCAGACAG (SEQ ID NO: 46) Human 187A5 F13: ACTGGCAGTTCGACATCACTCACCTG (SEQ ID NO: 47) Human 187A5 R4: GAGGAATTCCAGTACAAGGAAGGCATCTGGGC AGG

As a result of sequence determination, a protein encoding this human gene exhibited a high homology to the mouse 187A5 protein over the whole region and had 77% amino acid identity and 87% amino acid homology. Therefore, this gene is thought to be a human 187A5 homologous gene (SEQ ID NO: 1).

Example 2 Expression Analysis by In Situ Hybridization of 187A5 Gene

In order to investigate the expression pattern of the 187A5 gene in detail in the cells of dopaminergic neuron lineage, expression analysis of mRNAs of 187A5 and Lrp4 was performed by in situ hybridization according to the following protocol.

First, a DIG-probe was produced by the following method.

From a 12.5-day mouse (obtained from SLC) embryo, the mesencephalon metencephalon region was cut out. The total RNA was prepared by using the RNeasy mini kit (Qiagen), and double-strand cDNA was synthesized by using the cDNA synthesis kit (TAKARA). Next, by using the synthesized cDNA as a template, cDNAs of 187A5 and Lrp4 were amplified in the following reaction system.

10xExTaq 5 μl 2.5 mM dNTP 4 μl ExTaq 0.25 μl 100 μM primer 0.5 μl for each cDNA 1 μl DMSO 1.5 μl Distilled water 37.25 μl

The amplification was carried out under the conditions that incubation was performed for 5 minutes at 94° C., then reactions for 30 seconds at 94° C., for 30 seconds at 65° C. and for 2 minutes at 72° C. were performed at 35 cycles, and finally, incubation was performed for 2 minutes at 72° C.

The following primers were used in the PCR.

(SEQ ID NO: 48) 187A5: AGCTGAGCCACCTTCTCAGTCCAGAC (SEQ ID NO: 49) CCACGTCCAGGTCTTGACAAACCCAC (SEQ ID NO: 50) Lrp4: GACAGTGAACCTTTGGTCACTGATGG (SEQ ID NO: 51) GCCTTCCTGTCCTGGGATCAGCTTGG

The amplified cDNA fragments were cloned into pCRII (Invitrogen) and used as templates, and thereby, DIG-probes were synthesized in the following reaction system (all of the reagents were purchased from Roche).

RNA Polymerase Buffer 2 μl NTP Labeling Mix 2 μl RNase Inhibitor 1 μl RNA polymerase (T7 or SP6) 2 μl Template DNA 1 μg Distilled water Total 20 μl

After 2 hours at 37° C., DNaseI (Roche) treatment was performed for 15 minutes at 37° C., and the DIG-RNA probe was collected by ethanol precipitation.

Next, a 12.5-day mouse embryo was excised and fixed for 2 hours at 4° C. by using 4% PFA (WAKO)/PBS. Then, the solution was replaced at 4° C. overnight by 20% sucrose (WAKO)/PBS, and then, the embryo was embedded with OCT (Sakura Seiki Co., Ltd.). Sections of 12 μm thickness were prepared, dried on slide glasses, and then fixed again for 30 minutes at room temperature by using 4% PFA. After rinsing with PBS, hybridization (1 μg/ml DIG-RNA probe, 50% formamide (Nacalai Tesque, Inc.), 5×SSC, 1% SDS, 50 μg/ml yeast RNA (Sigma), 50 μg/ml heparin) was performed for 40 hours at 68° C. Then, rinsing (50% formamide, 5×SSC, 1% SDS) was performed at 68° C., and further rinsing (50% formamide, 5×SSC) was performed at 68° C. After rinsing with 1×TBST at room temperature, blocking (blocking agent: Roche) was performed. An alkaline phosphatase-labeled anti-DIG antibody (DAKO) was reacted therewith at 4° C. overnight, and after rinsing (1×TBST, 2 mM levamisole), NBT/BCIP (DAKO) was used as the substrate for coloring.

As a result, in the 12.5-day mouse embryo which is in the period of generating dopaminergic neurons, it became revealed that mRNA of 187A5 is selectively expressed in the mesencephalon most ventral ventricular zone (ventricular zone: VZ) in which the Lrp4-positive dopaminergic neuron progenitor cells exist and the mesencephalon most dorsal roof plate region (FIG. 4). On the other hand, the expression was not recognized in the metencephalon ventral region. Therefore, it was confirmed that mRNA of 187A5 is not expressed in the metencephalon floor plate cells positive for Lrp4.

From the above-described results, it became revealed that mRNA of 187A5 is selectively expressed in the dopaminergic neuron proliferative progenitor cells. Cells simultaneously expressing both of the Lrp4 and 187A5 genes are limited to the dopaminergic neuron proliferative progenitor cells that exist in the mesencephalon most ventral ventricular zone. Therefore, it is thought that the dopaminergic neuron proliferative progenitor cells can be discriminated with higher accuracy by using these markers in combination.

Example 3 Expression of 187A5 Gene in Dopaminergic Neurons Induced to Differentiate from ES Cells

Whether or not the 187A5 gene is expressed when ES cells are induced to differentiate into dopaminergic neurons in vitro was studied.

First, according to the SDIA method (Kawasaki et al. Neuron. 2000 October; 28 (1): 31-40), ES cells (mouse-derived CCE strain provided from Mr. Nishikawa in Riken CDB, Kawasaki et al. Neuron. 2000 28 (1): 31-40.) were induced to differentiate into dopaminergic neurons. Lrp4-positive and Lrp4-negative cells were separated from the cells in the sixth day after the induction (Example 5 of WO 2004/065599), and the total RNA was prepared from the cells immediately after the separation. By using this total RNA as a template, cDNA was synthesized and amplified.

Moreover, according to the 5-stage method (Lee et al. (2000) Nat. Biotech. 18: 675-679, mouse dopaminergic neuron differentiation kit (R & D Systems)), ES cells (CCE) were induced to differentiate into dopaminergic neurons. Lrp4-positive and Lrp4-negative cells were separated from the cells in the seventh day of stage 4 (Example 8 of WO 2004/065599), and the total RNA was prepared from the cells immediately after the separation. By using this total RNA as a template, cDNA was synthesized and amplified.

Next, by using the cDNAs corresponding to the amplified cDNA of 4 ng, 0.4 ng and 0.04 ng as templates, PCR was performed in the following reaction system.

10xExTaq 1 μl 2.5 mM dNTP 0.8 μl ExTaq 0.05 μl 100 μM primer 0.1 μl for each cDNA 1 μl DMSO 0.3 μl Distilled water 6.65 μl

After incubation for 2 minutes at 94° C., the amplification reactions were performed for 30 seconds at 94° C., for 30 seconds at 65° C. and for 2 minutes at 72° C., and finally, incubation was performed for 2 minutes at 72° C. The amplifications of PCR were performed at 26 cycles.

The following primers were used in the PCR.

(SEQ ID NO: 33) Lmx1a: TGGTTCAGGTGTGGTTCCAGAACCAG (SEQ ID NO: 52) TCTGAGGTTGCCAGGAAGCAGTCTCC

In addition, for Lrp4 and 187A5, the primers of Example 1 were used.

As a result, it was confirmed that the 187A5 gene is expressed in the differentiation induction by any of the methods, and strongly expressed, particularly, in the Lrp4-positive cells (FIGS. 5 and 6). Therefore, it became revealed that mRNA of 187A5 is expressed in the dopaminergic neuron progenitor cells not only in the cells derived from the mouse and rat embryonic mesencephalons but also in the cells induced to differentiate by any of the SDIA method and the 5-stage method. Specifically, it became revealed that the 187A5 gene serves as a useful marker for discriminating not only the dopaminergic neuron progenitor cells derived from the embryonic mesencephalon but also the dopaminergic neuron progenitor cells induced to differentiate from ES cells in vitro.

Example 4 Expression of 187A5 Protein on Cell Surface

In the 187A5 protein, a sequence that is thought to be a transmembrane region exists at one site. If the 187A5 protein is expressed on the cell surface, 187A5-positive live cells can be separated by flow cytometry using an antibody capable of binding to the 187A5 protein and are expected to be useful in preparation of a transplant material for the Parkinson's disease or the like. Therefore, the intracellular localization of the 187A5 protein was studied.

(1) Analysis of Signal Sequence

In the case of a type I transmembrane protein, a signal sequence generally exists in the neighborhood of the N-terminal and is cleaved off immediately after the signal sequence, and thereby, the protein can be expressed on the membrane. As a result of computer search (PSORT II, http://psort.ims.u-tokyo.ac.jp/form2.html), a sequence that is predicted to be a signal sequence was not found in the mouse 187A5 gene. On the other hand, a signal sequence-like sequence existed in the neighborhood of the N-terminal of the human 187A5 gene. Therefore, whether a functional signal sequence exists in the 187A5 gene was studied.

A construct in which a region encoding the amino acids from the N-terminal to amino acid 45 in mouse cDNA was linked to signal sequence-deficient secreted alkaline phosphatase cDNA was prepared and transfected into 293E cells. A culture supernatant in the fourth day of culture was collected, and alkaline phosphatase activity was measured by using the Aurora kit (ICN) (FIG. 7).

As a result, when signal sequence-deficient secreted alkaline phosphatase (control) is expressed, this protein is not secreted. Therefore, alkaline phosphatase activity is not recognized in the supernatant. By contrast, in the case of the fusion protein in which the N-terminal sequence was linked, strong activity was recognized in the supernatant. Therefore, it became revealed that the fusion protein is efficiently secreted by the N-terminal sequence of 187A5 (FIG. 8). Therefore, it became revealed that a functional signal sequence exists in the neighborhood of the N-terminal of 187A5. This indicates that the 187A5 protein is a type I single transmembrane molecule.

(2) Expression of 187A5 on Cell Surface (Biotinylation Method)

In order to confirm whether or not the 187A5 protein is expressed on the cell surface, whether the 187A5 protein is biotinylated when only proteins on the cell surface are biotin-labeled was studied.

A construct in which an HA tag was added to the C-terminal of 187A5 was transfected into NS20Y cells. After 2 days, the cells were rinsed with cold PBS twice, and then, 5 ml of 0.5 mg/ml EZ-link Sulfo-NHS-SS-Biotin (PIERCE) (dissolved in PBS+1 mM CaCl₂, 0.5 mM MgCl₂) was added thereto. The reaction was performed for 30 minutes at room temperature. After rinsing with cold PBS twice, the cells were collected, then suspended in 600 μl of a dissolution buffer (1% SDS, 10 mM Tris-Cl, 100 mM NaCl, 1 mM EDTA), and subjected to ultrasonication. After centrifugation for 3 minutes at 14000 rpm, the supernatant was collected. 20 μl of streptavidin beads (PIERCE) was added thereto, and after rotation for 1 hour at room temperature, rinsing was performed with a dissolution buffer twice. To the beads, 75 μl of SDS-PAGE sample buffer was added, and after 3 minutes at 100° C., the bound proteins were collected by centrifugation. The 187A5 protein was detected by western blotting using an anti-HA antibody (Roche).

As a result, it became revealed that the 187A5 protein is biotinylated with high efficiency (FIG. 9). Therefore, it is thought that the 187A5 protein is expressed on the cell surface.

(3) Expression of 187A5 on Cell Surface (FACS Analysis)

Whether the 187A5 protein can be detected by a FACS method was studied. A construct in which cDNA encoding the C-terminal side from the predicted cleavage site (amino acid 39) of 187A5 was linked immediately after a signal sequence of Preprotrypsin and a sequence encoding a FLAG tag was prepared. By expressing this construct, 187A5 in which the FLAG tag is added to the N-terminal can be expressed after the cleavage of the signal sequence. This construct was stably introduced into B300.19 cells through retrovirus vectors. The parent cells and transformants were rinsed with a FACS buffer (PBS+1% fetal bovine serum (JRH)+1 mM EDTA). Then, reaction with 10 μg/ml anti-FLAG antibody (SIGMA) was performed for 30 minutes on ice, and rinsing was performed with a FACS buffer. Sequentially, reaction with a PE-labeled anti-mouse IgG antibody (Jackson) (diluted to 1/200) was performed for 30 minutes on ice, and rinsing was performed with a FACS buffer. After staining, analysis was performed by flow cytometry (FACS calibur, Becton Dickinson).

As a result, unlike the parent strains, a population that strongly reacts with the FLAG antibody was detected in the stable transformants (FIG. 10). Therefore, it became revealed that 187A5 is expressed on the cell surface in a direction wherein the N-terminal side thereof can be located in the extracellular space, and can be detected by FACS using an antibody. Specifically, it is thought that 187A5 is useful as a marker for separating dopaminergic neuron progenitor cells as live cells.

Example 5 Expression Analysis of 187A5 Protein

By using a gene sequence encoding the extracellular region in the 187A5 gene, an anti-187A5 antibody was produced according to the following protocol, and expression analysis was performed by immunohistologic staining.

First, a gene sequence encoding the extracellular region (amino acids 1 to 919 of SEQ ID NO: 15) in the mouse 187A5 gene was gene-transfected into 293E cells, and the extracellular region of the 187A5 protein was expressed and collected. A rat was immunized with the collected protein, and then, lymphocytic cells were extracted and cell-fused with myeloma cells. From the fused cell population, a clone capable of reacting with 187A5 was selected. An anti-187A5 monoclonal antibody was purified from a culture supernatant of this clone. Next, an 11.5-day mouse embryo was fixed for 2 hours at 4° C. by using 4% PFA/PBS (−). Then, the solution was replaced at 4° C. overnight by 20% sucrose/PBS (−), and then, the embryo was embedded with OCT. Sections of 12 μm thickness were prepared, mounted on slide glasses, then dried for 30 minutes at room temperature, and moistened again with PBS (−). Then, blocking (25% Blockace (Dainippon Sumitomo Pharma Co., Ltd.)) was performed for 30 minutes at room temperature. The prepared anti-187A5 monoclonal antibody (culture supernatant diluted 2-fold, 2.5% Blockace/PBS) was reacted therewith for 2.5 hours at room temperature, and then, rinsing was performed for 10 minutes at room temperature four times by using 0.01% Triton X-100/PBS (−). A Cy3-labeled anti-rat IgG antibody (Jackson, 10 μg/ml, 2.5% Blockace/PBS) was reacted therewith for 1 hour at room temperature, and rinsing was performed in the same manner. Then, rinsing with PBS (−) was performed for 5 minutes at room temperature, and sealing was performed.

As a result of expression analysis by immunohistologic staining using the prepared anti-187A5 monoclonal antibody, as with the results of Example 2, the existence of the 187A5 protein was recognized in the mesencephalon ventral region of E11.5 which is in the period of generating dopaminergic neurons, and was not recognized in the metencephalon ventral region in which dopaminergic neurons are not generated (FIG. 11).

From these results, it was confirmed that the 187A5 protein exists in dopaminergic neuron progenitor cells.

Example 6 Detection of Cell in which 187A5 Protein Exists

By using the anti-187A5 monoclonal antibody prepared in Example 5, cells in which the 187A5 protein exists were detected by flow cytometry.

First, the mesencephalon and metencephalon ventral regions of a mouse E12.5 embryo were dispersed by using the cell dissociation buffer (Invitrogen), and then, without being subjected to fixation and permeabilization treatments, the cells were stained for 20 minutes at 4° C. by using the anti-187A5 monoclonal antibody (purified antibody diluted to 1/10, 1% fetal bovine serum, 1 mM EDTA/PBS) and an anti-Lrp4 antibody (culture supernatant diluted to 1/2, 1% fetal bovine serum, 1 mM EDTA/PBS). Then, by using 1% fetal bovine serum and 1 mM EDTA/PBS-, rinsing was performed for 3 minutes at 4° C. three times. The cells were stained for 20 minutes at 4° C. by using a biotin-labeled anti-Armenian hamster IgG antibody (Jackson, 10 μg/ml, 1% fetal bovine serum, 1 mM EDTA/PBS), and rinsing was performed in the same manner. Then, the cells were stained for 20 minutes at 4° C. by using APC-labeled streptavidin (Pharmingen, 8 μg/ml, 1% fetal bovine serum, 1 mM EDTA/PBS) and a PE-labeled anti-rat IgG antibody (Jackson, 20 μg/ml, 1% fetal bovine serum, 1 mM EDTA/PBS), and rinsing was performed in the same manner. After the staining, detection was performed by using a flow cytometer.

As a result of flow cytometry by using the prepared anti-187A5 monoclonal antibody, a cell population in which the 187A5 protein exists was detected (FIG. 12). Here, the cells in which the 187A5 protein exists can be detected without being subjected to fixation and permeabilization treatments. Therefore, it was suggested that the cells in which the 187A5 protein exists can be separated as live cells by using a flow cytometer equipped with a cell sorter. Moreover, it was confirmed that the 187A5 protein exists in all of the mesencephalon Lrp4-positive cells, namely, the dopaminergic neuron progenitor cells. On the other hand, it was confirmed that the 187A5 protein does not exist in the metencephalon Lrp4-positive cells which do not contain dopaminergic neuron progenitor cells (FIG. 12).

From these results, it was shown that the 187A5 antibody is useful for separating dopaminergic neuron progenitor cells.

Example 7 Expression of 187A5 Protein in Dopaminergic Neurons Induced to Differentiate from ES Cells

The group of the cells containing the dopaminergic neuron progenitor cells induced to differentiate from ES cells in vitro by the SDIA method was dispersed by using the cell dissociation buffer (Invitrogen), and then, without being subjected to fixation and permeabilization treatments, the cells were stained for 20 minutes at 4° C. by using the anti-187A5 monoclonal antibody (purified antibody diluted to 1/10, 10% knockout serum replacement, 1% fetal bovine serum, 1 mM EDTA/SDIA differentiation medium) prepared in Example 5 and an anti-Lrp4 antibody (culture supernatant diluted to 1/2, 10% knockout serum replacement, 1% fetal bovine serum, 1 mM EDTA/SDIA differentiation medium). Then, by using 10% knockout serum replacement, 1% fetal bovine serum and 1 mM EDTA/SDIA differentiation medium, rinsing was performed for 3 minutes at 4° C. three times. The cells were stained for 20 minutes at 4° C. by using a biotin-labeled anti-Armenian hamster IgG antibody (Jackson, 10 μg/ml, 10% knockout serum replacement, 1% fetal bovine serum, 1 mM EDTA/SDIA differentiation medium), and rinsing was performed in the same manner. Then, the cells were stained for 20 minutes at 4° C. by using APC-labeled streptavidin (Pharmingen, 8 μg/ml, 10% knockout serum replacement, 1% fetal bovine serum, 1 mM EDTA/SDIA differentiation medium) and a PE-labeled anti-rat IgG antibody (Jackson, 20 μg/ml, 10% knockout serum replacement, 1% fetal bovine serum, 1 mM EDTA/SDIA differentiation medium), and rinsing was performed in the same manner. After the staining, 187A5- and Lrp4-expressing cells were detected by using a flow cytometer.

As a result of flow cytometry, a cell population in which the 187A5 and Lrp4 proteins exist was detected in the same manner as the mouse embryonic mesencephalon (FIG. 13).

From these results, it was shown that the 187A5 antibody is also useful for separating dopaminergic neuron progenitor cells derived from ES cells.

Example 8 Separation of Lrp4-Expressing Cell by Using Antibody

In order to confirm that the separated 187A5/Lrp4-copositive cells differentiate into dopaminergic neurons, the following experiment was performed by using Nurr1, a postmitotic dopaminergic neuron precursor cell marker.

The cells separated after being induced to differentiate from ES cells in vitro by the SDIA method were inoculated onto a slide glass coated with poly-L-ornithine (Sigma, 0.002% in PBS), laminin (Invitrogen, 2.5 μg/ml in PBS) and fibronectin (Sigma, 5 μg/ml in PBS), and cultured for 6 days at 37° C. in N2 (Invitrogen, 1×), B27 (Invitrogen, 1×), ascorbic acid (Sigma, 200 uM) BDNF (Invitrogen, 20 ng/ml) and 10% knockout serum replacement (Invitrogen)/SDIA differentiation medium. The cultured cells were fixed for 20 minutes at 4° C. by using 2% PFA/PBS, and rinsing with PBS was performed for 10 minutes at 4° C. twice. Then, permeabilization treatment with 0.3% Triton X-100/PBS was performed for 30 minutes at room temperature, and blocking was performed for 20 minutes at room temperature with 10% normal donkey serum/Blockace. Sequentially, reaction with an anti-Nurr1 antibody (in house culture supernatant diluted to 1/1000, 10% normal donkey serum, 2.5% Blockace, 0.1% Triton X-100/PBS) and an anti-HuC/D antibody (Molecular Probe, 1/50, 4 μg/ml, 10% normal donkey serum, 2.5% Blockace, 0.1% Triton X-100/PBS) was performed for 1 hour at room temperature, and sequentially, the reaction was performed overnight at 4° C. On the next day, by using 0.1% Triton X-100/PBS, rinsing was performed for 10 minutes at room temperature four times. Then, reaction with an FITC-labeled anti-mouse IgG antibody and a Cy3-labeled anti-rat IgG antibody (all Jackson, 3 μg/ml, 10% normal donkey serum, 2.5% Blockace, 0.1% Triton X-100/PBS) was performed for 1 hour at room temperature. Then, rinsing was performed in the same manner, and rinsing with PBS was performed for 5 minutes at room temperature. After sealing, the cells were observed.

As a result of culturing the cells separated by flow cytometry for 6 days in vitro, evidently many Nurr1-positive dopaminergic neurons were induced, compared to unseparated cells as controls (FIG. 14).

From these results, it became revealed that the 187A5/Lrp4-copositive cells were certainly progenitor cells of dopaminergic neuron lineage and can be matured in vitro. 

1. An antibody bound to a protein on a dopaminergic neuron progenitor cell wherein the protein is selected from the following (i), (ii), and (iii): (i) a protein comprising the amino acid sequence of SEQ ID NO: 2; (ii) a protein which is encoded by a polynucleotide which hybridizes under stringent conditions to a polynucleotide consisting of a complementary sequence of a nucleotide sequence of a polynucleotide encoding the amino acid sequence of SEQ ID NO: 2, wherein said stringent conditions comprise hybridization at 65 to 68° C. and washing in 0.2×SSC, 0.1% SDS; and (iii) a protein which consists of an amino acid sequence having 70% or more identity with the amino acid sequence of SEQ ID NO:
 2. 2. The antibody of claim 1, wherein the dopaminergic neuron progenitor cell is a dopaminergic neuron proliferative progenitor cell. 